Kokoro

Kokoro (ココロ) is one of the main characters in DARLING in the FRANXX. She is a former Parasite with the codename "556" of the Thirteenth Plantation, where she was partnered in boy-girl pair with Mitsuru to pilot a FRANXX called Genista and she was previously partnered with Futoshi.

Over time, she began an intimate relationship with Mitsuru and they had a wedding ceremony but were punished by having their memories altered. Despite this, they reconciled after learning she was pregnant with his child and they formally married. Together, they have four children; a girl named Ai who resembles her, a boy who also takes more after her, another girl who resembles Mitsuru, and an unborn child.

Appearance
Kokoro is considered to be an attractive fair-skinned girl with long, wavy ashen-blonde hair that has long bangs framing her forehead. She has a lacy blue headband to keep her hair out of her face and calm, rich blue eyes.

When piloting her FRANXX Genista, she wears a white bodysuit with light green accents and keeps her hair in a braided ponytail.

In Episode 24, during her pregnancy, Kokoro was usually seen with a braid laid on her right shoulder without wearing her headband. She also wore pregnancy clothes which were given to her to use from 007.

As an adult, her hair is cut to shoulder-length, she wears a white and tan colored dress with ruffled hems, her blue laced headband and her wedding ring on her left ring finger.

Personality
Kokoro is a very kind girl who has a gentle and optimistic personality to match and she is interested in plants and she is very knowledgeable in the "language of flowers". She doesn't speak too often, choosing to think before speaking, and thinks about others more than herself. Her kindness is treated with a welcome by her more feisty comrades. During scenes of tension, she is never the breaker or starter and sits by watching usually. She was depicted as someone going with the flow, which is seen when she couldn't voice her disapproval when Squad 13 explored the ruins of a town and during the Girls vs Boys fight. She also had an inability to speak out her mind and performance to avoid conflict due to her dislike of arguments. For that reason, she comes off as timid and sweet, as her strong kindness makes it appear she lacks the confidence to be confrontational, even in situations where she may disagree with her comrades. Miku states that Kokoro gets influenced by others so easily. Kokoro isn’t the type of person to seek attention and prefers to be treated no less than others, as she initially refused to get special treatment during her pregnancy but relented on the grounds she will be a pioneer to the other parasites; when she became surrounded by other girls who were fascinated by her and she, in turn, began teaching them how to sew as a way to befriend them. She gets along with her comrades very well and treats them with kindness, which makes her easily liked. Like the other kids, she didn't know how to translate her feelings of love due to her sheltered upbringing and, as a result, she didn’t know how to make it known to Mitsuru that she is in love with him. Even when he used to act cold towards her and the others, she never gave back any negative retaliation and felt a strong desire to help him with his personal problems, especially after learning he risked his life to receive an injection to become a parasite.

Despite her meek and gentleness, Kokoro holds back a myriad of feelings, admitting to Mitsuru that she is often dishonest with most around her. The incident where she feigned loyalty to Futoshi by breaking her promise to be partners with him forever by partnering with Mitsuru instead left her feeling bad. She even admits that she's not the sweet, innocent and nice girl everyone thinks she is. Even if she wanted to help Mitsuru, she still knowingly hurt Futoshi and claimed that it would be right for him to get angry with her. Through dishonesty with Futoshi, she reforms herself a little in praising Mitsuru for being so outspoken and honest with her about his suffering and lack of trust in others, and offering him words of encouragement to help him with his problems.

Through her interactions with Mitsuru, Kokoro slowly becomes more assertive and begins to honestly speak her mind, which is noticed when she reasons with the girls why they need to end the feud with boys and later openly questioning how they, as humans, were really born. A notable trait is also that she becomes much bolder, more straightforward and somewhat impulsive, which is seen where after Mitsuru had said some very nice words to her, Kokoro simply kissed him in response, and when he had said he would miss Mistilteinn because they got to spend more time together, she tried initiating sex with him. After finding a book on pregnancy and childbirth, Kokoro develops a fascination with it and wonders why humans stopped having babies. Knowing her purpose in life is to pilot the FRANXX and to die in battle, Kokoro develops a desire to bear a child to leave a mark for the future before she dies and she comes to believe having a child represents hope for the future. She also explicitly lets Mitsuru know of her desire to join her body with his and create a new life. Through this discovery, Kokoro gradually begins to question if her purpose in life is truly to only pilot the FRANXX and die for the sake of adults who don’t acknowledge them as individuals but as tools for warfare, and she expresses skepticism towards the ideals of Papa and the adults. She even admits she truly believes they are able to live a life beyond the FRANXX and forge their own destiny, an argument that deeply touches her friends and inspires them to find the courage to stand up to the adults.

As her partnership with Mitsuru develops into a romantic and sexual relationship, she becomes deeply attached to him and she is happy when they decide to get married, as she is confident they will find happiness despite knowing full well they are violating regulations and risking punishment. However, their wedding is interrupted by APE and their memories of each other are erased. She retains her kindness but is utterly focused on her duties and loyalty to Papa, and as a result is more distant with Mitsuru than anyone else. However, she becomes confused as she hears her friends say they fight to live for the sake of the future, which subconsciously causes her to be curious about her lost memories. Once she starts having painful flashes over saying Mitsuru’s name, she becomes frightened and reverts back to her obligation to fight even if it will cost her life. She pushes Mitsuru further away to the point of being cold to him while keeping a friendly atmosphere with the others. Upon learning she is pregnant with Mitsuru’s child, she is distraught at having lost her purpose in life (the ability to pilot the FRANXX) and rejects Mitsuru’s support because of their memory loss. Even when Mitsuru admits he wants her to keep the baby, she admits that she believes their memory loss serves as justification for him to have no obligation to be responsible and she had no anticipation that he would want to be. She also struggled to feel any affection for her unborn child and the indecision on whether to terminate the pregnancy or not left her deeply saddened. The despair at being unable to fulfill her duty as a pistil finally provoked Kokoro to admit to Mitsuru that she feels she has no purpose in life anymore and she is willing to go as far as to endanger herself and her baby to protect her friends and be useful. However, when Mitsuru tells her how much he truly cares about her and their child, Kokoro decides to keep the baby and reconciles with Mitsuru. Kokoro also implies she secretly wanted to rekindle their relationship by keeping her wedding ring after taking it off. Although his concern for her borders to overprotectiveness, Kokoro begins to warm up to Mitsuru and she comes to truly appreciate his support and, when her daughter is born, Kokoro is shown to be genuinely happy. The birth of their daughter ultimately brings them closer together. They are able to form a genuinely happy marriage and they have three more children together. As a wife and mother, she is affectionate and devoted to Mitsuru and their children.

Background
Like the other parasites, Kokoro was raised in the Garden to become a Pistil. She received the code name of "556," indicating that she did not receive special treatment from the adults. At some point, Hiro gives her the name of "Kokoro”. She is also shown to have been close friends with Miku ever since childhood and the two shared a mutual interest in flowers as Miku made Kokoro a flower crown as a gift.

Several years later, at age 14, upon being discharged from the Garden, she was assigned to Plantation 13 and paired with Futoshi.

Episode 01: Alone and Lonesome
The Parasites of Squad 13 discuss about the "Partner Killer" whose partner will die after the third time. Futoshi says he wouldn't ride with her. Goro walks in and asks if Ichigo got a hold of Hiro and she replies that she didn't. Futoshi says that he didn't attend that day's briefing, so maybe he's going to turn down the chance. Kokoro says it's sad if he leaves.

At Cerasus, the parasites attend their welcoming meeting where they are praised by Papa. The adults cheer for them. They then head by train for their startup ritual. Upon boarding their FRANXX, Kokoro and Futoshi give each other a thumbs up.

During a klaxosaur attack, Kokoro overwatches as Strelizia easily defeats it. They are shocked when it's revealed that Hiro was piloting it.

Episode 02: What it Means to Connect
Kokoro watches with the others as Zero Two pours honey over her food, much to Miku’s disgust. Kokoro notes how much Zero Two loves sweets but Miku remarks no ordinary person has horns like Zero Two. Nana then comes in to announce she will be their caregiver, which makes them happy. In the girls' changing room, Kokoro says that connecting in a FRANXX feels weird and hopes that they get used to it soon, since it's not at all like how their training units felt like. Miku fondles her stomach and describes it as her body being stirred up from the inside. Ichigo says it did feel a bit weird, but put her at ease like being one with someone. Kokoro says that she wishes her numbers were as high as hers and that she and Goro must be really compatible.

Hachi says he'll be giving overall strategic instructions and now begin the drill, and that field decisions will be made by the leader unit, Delphinium. As they connect, some of the pistils shriek lightly. Hachi tells them that if two partners are even slightly out of sync, their para-capacity will fluctuate wildly. Kokoro and Futoshi manage to connect in their FRANXX and they compliment each other. Kokoro later watches Hiro's mock exam battle against Miku and Zorome in their respective FRANXXs. Hachi declares it a draw.

Episode 03: Fighting Puppet
The Parasites discuss about the mock battle and if Hiro will truly be able to become a Parasite. Zorome and Miku begins to argue as they blame each other for their "loss". Kokoro warns them not to fight because it will affect their numbers.

Hachi later informs the Parasites that he received sortie orders from HQ. Nana tells them that the Klaxosaur won't be as big as the one they already saw. Hachi tells them that the klaxosaurs are attracted by magma energy reactions and appear in their vicinity. Lately, the klaxosaurs had been showing up deep in a Level 8 mine on the outskirts and wreaking havoc. Nana says that Strelizia won't be a part of the mission. Because they'll have to defend Plantation 13 by themselves eventually, so it can show whether they can handle fighting themselves in the future.

Kokoro connects with Futoshi and they head out along with only Delphinium and Argentea, since Chlorophytum had to stay behind. They head out to a big hole and marvel at it, realizing that they use the pipes to extract magma reserves. Hachi tells them to head down to the 8th floor to defeat it. They are able to defeat it but many more suddenly fall from the ceiling, so the Parasites plan on fleeing. Nana says that they attracted more because they released their magma energy. Zero Two says that she should have sent her from the start since they are now in a life or death situation. She gets permission to pilot, but with Mitsuru. Hachi soon tells them that Strelizia is about to help. Ichigo is bothered by this and causes them to fall, and this lets the klaxosaur to get in, so they flee. Many follow and a very large one is about to bite Ichigo. Strelizia appears and kills some and Mitsuru tells them to get back and Hachi tells them to evacuate.

When they retrieve Streliza, Kokoro sees Zero Two walking out, though Mitsuru is gravely injured and unconscious.

Episode 04: Flap Flap
Mitsuru had been traumatized with riding with Zero Two. When confronted by Hiro about it, he suddenly grabs Hiro's collar and says that she had a smile on her face all the time. Kokoro yells out to Mitsuru and Futoshi tells him to calm down as he hands the tray to Zorome. Mitsuru says that it will happen to Hiro too, if he decides to ride with her again and is out of his mind.

The Parasites later discuss about Hiro and Zero Two, as well as the partner killing rumor. Kokoro believes Hiro will still want to ride with Zero Two again and Miku criticizes her for saying that even after what happened to Mitsuru. Miku says Zero Two is not human because she possesses klaxosaur blood. Ichigo says Hiro is well aware of all these rumors and situations but he still wants to ride with Zero Two. Ichigo reminds everyone that if things do not change, they could also die at any time, to which Kokoro agrees on. Ichigo says that they need to defeat klaxosaurs without Strelizia and cannot mess up again so as to survive. Ichigo asks others to help her and work in a team.

To prepare for the kissing with Plantation 26, Plantation 13 switches to mobile setup. HQ soon detects a worm-type klaxosaur heading towards Plantation 13 and Hachi tells them to connect to defeat the klaxosaurs. They are ravaged by more klaxosaurs in hiding and are struggling, until Strelizia quickly saves them and destroys the klaxosaurs.

Episode 05: Your Thorn, My Badge
Cerasus carries out the kissing with Chrysanthemum and the parasites watch as the plantations connect.

The Parasites of the 13th and 26th Plantation attend a grand ceremony. The next day, Kokoro says that the ceremony on the previous day was so exciting that she couldn't sleep. Miku says that 090 seemed nice and Kokoro asks if she would like to ride with him. She says that it is better than the boys they are stuck with, and tries to get Ikuno's opinion. They later discuss about Hiro achievements in the battles so far and Kokoro praises him and says that he shone in the previous battle. Hiro later enters and tells everyone that he will try his hardest to fight alongside them all and not be a burden. This makes Mitsuru angry and he leaves, and Kokoro notices him walk.

During breakfast, Zero Two takes in Futoshi's seat, so Kokoro invites Futoshi to sit beside her. After praying and thanking Papa, Zero Two begins feeding Hiro to which Zorome says that he wants to try something like that. Goro asks why he does not ask Miku then. He says that he would rather ask a cute girl like Kokoro. He notices that she is feeding Futoshi, much to his annoyance. Miku teases that Kokoro is too easily influenced.

Later in the greenhouse, Kokoro sees Mitsuru as he panicky asks why Hiro could ride with Zero Two and not him. He takes pills and chokes on them. Kokoro, who wanted to irrigate the plants, says that she saw him walk in and she asks if he is okay. She offers him her help since he does not lean on others, but he interrupts and asks if she is pitying him. She denies this, but he walks past her and tells her to leave him alone.

Hachi later announces that Squad 13's and Squad 26's Parasites will fight the klaxosaurs that had been detected. He explains that there are 100 to 150, and that they are expected to arrive at 33 hours from then.

Episode 06: DARLING in the FRANXX
A large Klaxosaur crushes a tall building and approaches with an arrival time of 0210 hours. The bulwark in the last line of defense is 85 percent complete and will be completed by 2200 hours. Squads 26 and 13 are to stand by for combat by 2030.

Kokoro gets dressed as she says that the number of klaxosaurs is higher than estimated and wonders if they'll be okay and come back alive. In their FRANXX, Hachi announces that, besides from the Conrad-class pack, they've also detected a large, tightly packed unit. He gives 090 field command and tells Strelizia to stay back.

Squad 26 takes out a few klaxosaurs and 090 tells them to deal with them calmly. Four get through and he asks that Squad 13 takes care of them and advises them. The stamen comment on his attitude and Mitsuru agrees that they are really new to it. As battle begins, Argentea crashes into Chlorophytum causing Zorome and Mitsuru to bicker. Though Genista is almost attacked, Delphinium jumps in and kills the klaxosaur, to which Kokoro thanks Ichigo for. Ichigo asks Zorome to bait the enemy without getting too close, sice they're fast. She tells Mitsuru to stay close to Genista and back it up. Goro advises that she doesn't get too worked up. Strelizia then quickly defeats many klaxosaurs, but Zero Two and Hiro begin to disconnect.

Squad 26 begins attacking and the klaxosaur screams before becoming its Gutenberg-class humanoid form. 090 orders them to keep attacking, but they are roughly thrown into the ground. He orders them to get back, but he is unable to move as they're out of fuel. Before they are crushed, Argentea pulls them away. Hachi orders all squad 26 units to fall back and Squad 13 will deal with it. Though the group agrees that they need Strelizia, Ichigo orders that they stay put. She says it'll land the finishing blow. Zorome becomes angry, but Goro says that only Strelizia's spear can reach its core, so they'll make an opening for it. Ichigo privately thanks him for his plan. They begin crawling up it.

After Hiro recovered from his tumor, Strelizia creates an opening and defeats the klaxosaurs. Hiro and Zero Two walk out together and the squads groups celebrate.

Episode 07: Shooting Star Moratorium
After the successful kissing with Plantation 26, Squad 13 was given a special vacation. The kids seem happy and Futoshi and Zorome run to the water. Though Miku says that they're childish, Kokoro smiles and says that it's expected, as it's their first time seeing an ocean that's okay to swim in.

Kokoro serves a ball to Miku while Futoshi and Zorome admire their figures. Later, Miku and Kokoro call the group back since Mitsuru had found something "odd". Mitsuru leads the group through a thin pass, though Kokoro says that she's a bit scared of the dark. Mitsuru coldly replies that she didn't have to come if she didn't want to. Futoshi is angered by this and tells him to be nice to her, but Mitsuru says that he can't guarantee their safety. They're lead to what appears to be a city. Kokoro asks if people live there, and Mitsuru replies that he'd never heard of anyone living outside the plantations. As everyone starts to explore various areas, Futoshi wonders where Kokoro went. Kokoro is revealed to be alone and comes by a medical office. She finds a book about childbirth and is thereafter suddenly called out by Mitsuru and he pulls her back before a bookcase falls on her. He asks her not to run off alone and she apologizes. They walk back to the rest of the group and the Parasites discuss the city, confirming that it was part of civilization and that people in previous eras lived: on the surface. Back at the beach, food had been delivered. They all begin eating, and Miku teases Futoshi and Zorome by lying on Kokoro's lap. When Ichigo stands and officially welcomes Hiro and Zero Two to the squad, Kokoro says that she finds it reassuring that they're with them. The Parasites are then shown to sleep close together; Kokoro and Miku beside each other.

Episode 08: Boys × Girls
As the parasites are fighting a klaxosaur, it spews goo. It leaks into the cockpits and melts the girls' parasite suits. Though the boys begin spacing out, they don't tell the girls and they finish off the klaxosaur. Hiro finally tells Zero Two and the rest of the girls realize what's happened.

After the battle, the girls cover themselves with a towel and glare at their partners, except Kokoro who is just embarrassed. The boys look embarrassed, and Goro explains they only didn't tell because they didn't want to distract them during the battle. Futoshi says he didn't because he found Kokoro to be amazingly beautiful, to which Kokoro turns red and looks away.

As the girls shower, they discuss what happened and wonder how long they had been ogling them. Kokoro says they're taking things a bit too far, and Miku suggests that they should live separately. The girls then begin splitting the area of the house between the boys and girls. Zorome begins to cross but is threatened by Miku and stops. The girls talk about what's happened but notice that Zero Two is ignoring their split. As they go to reprimand her, the boys walk in from swimming in the lake wearing only boxers. Though Miku tells them to get dressed, he says they can do whatever they like on their side. As they clean the bath, Ichigo says that it must have been Goro's idea. When they go to eat, the boys are already there. Goro says that they've already taken over the area. Miku becomes annoyed, so Goro suggests that drop all the rules and eat together. Zero Two walks in and Miku attempts to follow her, but the other girls pull her back. When Kokoro enters the greenhouse, she finds Mitsuru. He slips his medication into his pocket and Kokoro asks if he has an interest in plants as she tucks her baby book into her pocket. He denies it, as it is only a good place for being alone. Kokoro then tells Mitsuru that she begged Nana to let her take care of the greenhouse. She tells him about the meaning of some of the flowers and then asks if he doesn't mind chatting with her when the girls and boys are "feuding." He says it's stupid and can't be bothered. Kokoro is amazed and says it takes a lot of courage to refuse to toe the line and she was too scared to say anything. Mitsuru doesn't react and instead decides to walk out, and as she stands up, she drops her book. She quickly hides it but Mitsuru says that it doesn't matter to him and walks out. At night, the girls get Zero Two to cooperate with them: she changes the girls only bath sign to allow boys and, when they enter naked, the girls are already bathing. They become angry and begin throwing bathing supplies at them. Kokoro doesn’t take part in the fight and instead hides in the bath. The parasites continue to bicker when Nana suddenly interrupts. She and Hachi scold the group after they get dressed. Later in the girl's room, Zero Two tells them if they half-ass things, they'll end up adults. She says to say what they want because they'll all die sooner or later before leaving the room.

Kokoro finally musters up her courage to speak up about the whole feud: she tells the other girls that they need to begin working together again after looking at her book. She says that despite how flawed the boys are, they can only do things when they are together with boys, including piloting the FRANXX and, blushing but not saying it, having children. Ichigo and Ikuno feel that it is unusual for her to be so assertive. Miku however, refuses to end the fight. She flees and when the others become worried and decide to look for her, they find her in one of the sealed off rooms in the dorm, where they discover items related to the previous members of Squad 13, which were possibly killed in battle long ago. Kokoro comforts Miku who cries. After that, the boys and the girls finally make amends and resume their duties together.

Episode 09: Triangle Bomb
The parasites are happy to receive their gifts from Papa: Kokoro receives a sewing kit. She and Miku are happy about their gifts and smiles.

Later, Hachi tells the Parasites that they've detected a Gutenberg-class Klaxosaur 2,000 from there. Everyone gets ready and the FRANXX approach the klaxosaur and attempt to defeat it, but the klaxosaur multiply its jelly, and Goro quickly pushes them out but is stuck instead. He quickly launches Ichigo before it explodes.

To save Goro, Genista, Chlorophytum and Strelizia all help Ichigo to save Goro and get him out of the klaxosaur. Everyone later overwatches as Ichigo treats Goro's wounds and as they share a moment together.

Episode 10: The City of Eternity
Nana explains that everyone in Squad 13 has to wear their formal clothing the next day as Papa is going to award them medals. The ceremony will be held in the Plantation Parliament HQ, which means they can go into the city.

The next morning, the kids stand at the door and they remark that Zorome looks cooler than usual. Zorome smugly agrees, and while the other boys mock him, Kokoro giggles and say that he does look a lot cooler. Miku tells Kokoro not to flatter him, causing she and Zorome to bicker again. Hachi and Nana open the door and they all leave. The children marvel at the city. At the ceremony, the mayor congratulates them and thanks to them for their efforts. After the ceremony, Kokoro and the other girls push Nana to let them walk back, and she reluctantly agrees. The children look around as they walk back, though Zorome wanders off and is separated. When Ichigo later announces that they found Zorome, everyone is relieved.

Episode 11: Partner Shuffle
As all the unit stands on guard, Futoshi tells Kokoro that they've grown stronger and Kokoro praises him by saying that it is thanks to him carrying her through. Futoshi says that she's his responsibility to which she giggles and thanks him. Blushing and nervous, he asks that she promise to be his partner forever, and Kokoro again smiles and agrees. Futoshi is happy and promises to always protect her. Miku suddenly interrupts and says he's gross, and Zorome agrees and says to cut off his comm. Kokoro giggles, but Futoshi reprimands them for listening.

After their fight, they discuss Mitsuru's recent condition and Goro remarks how he has always been fragile, and Ichigo adds that he was the only one who received the Elixir Injection, a highly concentrated drug that induced yellow blood cell production and greatly increases parasite aptitude, and came back alive. Kokoro says that the injection has only a survival rate of 15% and didn't know he had such a risky procedure.

Due to the possible incompatibility of Ikuno and Mitsuru, Nana suggests that they try a "partner shuffle", simply an option available to them. The children discuss their thoughts, and Futoshi says that they don't need to since he promised to protect her forever. He asks Kokoro about how she feels and she reluctantly agrees. Nana asks if there is anyone who wants to try piloting with a different partner; Ikuno asks to try a pistil-pistil connection as a backup plan when they've lost a stamen. Nana agrees to let them try and asks if there's anyone else. Kokoro shyly puts up her hand and asks to try with Mitsuru. This surprises everyone and Futoshi is hurt. He begins crying and Kokoro apologizes.

As they try out the new pairs, Genista's score crossed the minimum required, and though it is in the lower range, it is stable.

In the greenhouse, Kokoro twirls around and hums with her doll, to which she says that the flowers smell nice. Mitsuru suddenly asks what she's doing, and she throws her doll in surprise. They sit together and she asks why he thinks humans stopped having children since it seemed like having a baby was the most natural thing. Mitsuru replies that it's probably because they don't need to anymore, and he tells her not to waste time thinking about unnecessary things, as one look at the adults makes it clear: they don't need others to live. He then asks why she volunteered to be his partner since it's had become troublesome as Futoshi hated him now. He asks if it was out of pity, but Kokoro denies this. Before she can continue, they are interrupted by sirens.

A Gutenberg-class klaxosaur approaches and Hachi commands to set up a defensive line 500 meters from the S-Planning and neutralize the target. He says that Genista and Chlorophytum will act as rear support. As Kokoro and Mitsuru go to their FRANXX, Futoshi stops him and tells him to protect Kokoro. Mitsuru scoffs by his ridiculous statement accordingly to himself, and Kokoro stops Futoshi and says she'll be fine. Futoshi tells her to be careful and says he'll do his best with Ikuno to which Kokoro smiles and nods.

The FRANXXs begin to attack the klaxosaurs; three get past and Chlorophytum goes after it and manage to kill one. Mitsuru struggles as well, and Kokoro says that there's no need to rush. Strelizia kills another one for them and Hiro asks if they're okay. Kokoro thanks him, and he tells Mitsuru to hand in there before rushing back. Mitsuru becomes annoyed and charges blindly at the klaxosaur, causing them to smash into it. An operator announces that Genista's positive pulse is dropping below the minimum. Though they are about to be squished, Chlorophytum shields them. Futoshi says that he'll protect her as they shoot into its foot.

As Kokoro suggest that they should start over again, Mitsuru disconnects from the FRANXX and its power shuts down. He tells her that if she places her hopes in him, she'll only be let down because he's incompetent. She disagrees and enters them into radio silence. Kokoro says that he can rely on others more and that she wants to have a mutual understanding and believing between each other since they are partners. Mitsuru asks if she's joking. Mitsuru then proceeds to tell Kokoro about his past and promise with Hiro and how he was betrayed by him. As he holds his head in his hands and cries, Kokoro says that must have deeply hurt him and comforts him. She says that she acted similarly towards Futoshi and that she isn't the nice girl they think she is. She says that if someone did something like that to her, she wouldn't have any right to complain or blame them. He angrily asks if he should forgive him too, and she calmly replies that it's up to Mitsuru himself. She tells him that her point in saying this is that they aren't perfect as the adults, but she wants to have relationships with other people. As she says that she believes in him, she turns and begins to enter stampede mode. Mitsuru suddenly takes her out from her seat to prevent her from fully going into stampede mode. Her actions make Mitsuru shocked and he asks how she can trust someone so much. As Kokoro gives Mitsuru a wry smile, he remarks how unbelievable she is with a smile on his face.

Genista reconnects and they all work together to kill it. After the battle, Futoshi walks about to Mitsuru and asks why he was so reckless. Although Kokoro attempts to stop Futoshi, Mitsuru stops her. Futoshi punches Mitsuru in the face and Kokoro rushes to care for him. Futoshi shouts at him before Mitsuru slowly says that he promises to protect Kokoro from now. This surprises Kokoro and Futoshi falls to his knees and says that he loved her.

Episode 12: The Garden Where It All Began
The members of Squad 13 looking out of a large window, seeing the Garden, a parasite development facility where hundreds of children live where they grew up, as they approach it. They walk into the lab and Kokoro comments that very few children got to enter, though Hiro states that he did a few times. Nana then tells them that they were brought to run tests on them and says that they are banned from entering the Garden. Hiro says that they're probably just tagging along with Zero Two. Hachi confirms that she, in particular, will undergo thorough testing.

The Nines appear and 9'α says Zero Two must be there for maintenance as well, but she ignores them. Kokoro wonders who he is and Miku says he is handsome. Nana introduces them and through their conversation with Alpha, the Parasites realizes that the plantations on the continent are currently heading to a particular place.

Disobeying orders, Kokoro, with the other members of Squad 13, visit the old facilities where they were raised in, hoping to meet Naomi again. While Kokoro and Miku stroll around the Garden and see the kids being raised there, it makes them reminisce about their own childhoods. While exiting the Garden, Kokoro starts to wonder where all humans, including themselves, came from. She voices this to the others, but they are indifferent since everyone is convinced that Papa made them.

The next days, Genista is seen on missions along with the other FRANXXs. They are unaware of what is happening with Hiro and Zero Two.

Episode 14: Punishment and Confession
As Zero Two and Hiro realize they knew each other as children, Ichigo suddenly interrupts and throws her off of him and tries to revive Hiro. The other FRANXX wait. Zero Two later goes to talk to Hiro but is stopped by Ichigo. She blames her for his hospitalization and says she can't see him again. When Ichigo reveals that Hiro will lose his humanity, the rest of the parasites don't believe her and ask Zero Two. She tells them to shut up and mind their own business. Ichigo stops her again from seeing him and says that she isn't a member of their team. When Hiro wakes up, he is surrounded by his teammates.

Hachi announces they must neutralize every klaxosaur inhabiting Gran Crevasse. Nana says that it is a joint operation with the 9's and FRANXX squad from each plantation. He says that Squad 13 is scheduled to be part of the sixth wave. Ichigo then asks for Zero Two to be removed from Squad 13 as of that mission and, if not, Squad 13 will not participate in the operation. Nana says that she was set to return to the 9's as of the mission anyway. Zero Two protests, but the Parasites stop her from seeing Hiro.

When Zero Two starts to show how much she wants to meet Hiro and talk to him, Ichigo is reluctant but Kokoro and Goro want to let her see him, stating that it's sad to see them apart. Goro says that she can meet him, but they're all going to be there. When they enter the room, it's empty since Hiro had escaped. Zero Two becomes enraged and says that they tricked her, and she proceeds to attack the Parasites unconscious. Hiro later walks in and scolds her for being such a monster.

Kokoro and the other Parasites watches Zero Two as she leaves the plantation.

Episode 15: The Bird that Shares Wings
At Cerasus's international briefing room, Hachi explains that their objective is to take control of Gran Crevasse. Though another group is attacking, they aren't making headway and Squad 13 is to group up with squads from other plantations. Kokoro asks what Gran Crevasse is to which Nana shows them a video where a sheer number of klaxosaurs are. Hachi explains that taking over Gran Crevasse is Papa's long-standing wish and would be a turning point in humanity's history.

In Cerasus's command room, the Parasites receive a message from mission command saying they're prepared to sortie. After a while of fighting, a big klaxosaur releases smaller klaxosaur inside the 13th Plantation. The FRANXX struggle against their large numbers and Zero Two takes out a large number of klaxosaurs. Kokoro says that they're being pushed back, but suddenly, everyone notices a training unit zip by them, realizing it's Hiro. Delphinium takes Hiro to Zero Two.

As Genista and Argentea attack klaxosaurs, one of the cores crack in half and something falls out of the centre to which Ikuno comments it looks like a human. Suddenly, there is an explosion and it is announced by Papa that the backup plan is almost complete, and he says that they can let the plantation go now. The stamen of the plantation are confused as to why they're making in plantations self-destruct. The Nines comment that APE is planning to end things without Strelizia's help.

Later, Zero Two and Hiro reconcile. Everyone is emotional and happy for them. Strelizia attacks and easily takes out the klaxosaur. The 9's begin attacking as well. The sages say that the door to Gran Crevasse has been opened and the day of humanity's liberation is upon them. Inside the mountain klaxosaur, they find that its core is a collective mass of cores. A large hand suddenly shoots up from the ground and it smashes a majority of the plantation, leaving Mistilteinn in ruins.

Episode 16: Days of Our Lives
After the battle, the 13th Plantation was left in ruins and the Parasites still continue living in Mistilteinn. They stand by and wait for their next mission, though one month has passed since they were given those orders. Futoshi comments that the damage to the plantation has affected the water supply system, and they had to restrict their electricity usage. Their caretakers were gone too and only the food supply is delivered once a week. Kokoro, Futoshi and Miku help with the laundry. Zero Two suddenly bangs a spoon against a pot to which Kokoro and Miku realize that she's on messenger duty this week.

After breakfast, Kokoro went to the greenhouse to water the plants, and Mitsuru suddenly came to Kokoro and asked her to cut his hair. She was confused, questioning where that request came from but upon seeing Mitsuru timidly look down, she merrily accepted. As she cuts, Mitsuru wondered what he was hoping for with Hiro. He admitted that he was wrong and was probably using his grudge to carve out a niche for himself and now he has nothing. When she is done cutting, Kokoro tells him to look up and giggles when he looks. He asks if he looks weird, but she says he looks handsome. Kokoro gives him some words of comfort and says that if he understands that, he can start over. He smiles and says her saying that makes him feel like he can do anything, she's kind and gifted with her hands. Kokoro blushes and gets down on her knees and kisses him. Mitsuru is quite surprised and does not say anything. Kokoro, embarrassed, apologizes and runs away.

The girls bathe in the river. Miku asks if they have seen Mitsuru's hair, and as Kokoro becomes flustered, Miku realizes that it was Kokoro who cut it. Kokoro laughs.

The parasites meet in their living room and discuss their livings conditions. Kokoro points out how all their needs, such as food and clothes, were always provided to them until now. They sadly reflect on their vulnerability, so Zero Two says that they should cook their own food and everyone agrees. Everyone helps out with dinner: Kokoro makes a salad and Mitsuru makes a dressing. When Hiro, Goro, and Zero Two comes back from fishing, Kokoro is impressed by their catches, especially Zero Two's. She and the others ask to fish as well. When Zero Two shows them the tricks to fishing, Kokoro is unsure if she can pull it out. Before they eat, they all marvel at how they were able to cook. Miku tries Kokoro's salad and says it's good, which makes Kokoro happy and she and Mitsuru smile at each other. Zorome is happy at what they've accomplished and tries to get Futoshi to eat. Futoshi accidentally drops the food and Mitsuru asks if he's okay. As he picks glass, Zorome tells him to quit forcing himself since he knows that Futoshi is forcing himself to eat and throwing it back up. Though Futoshi denies it, Zorome grabs his collar and begins crying and tells him to eat to survive. Zorome asks why Papa isn't getting in touch as he cries.

Later at evening, Mitsuru says that as FRANXX pilots, there's a limit to their lives. Miku cries as she says that she was worried too, but too scared to speak up. Kokoro leans against her. Everyone talks about their worries and Hiro then comments that it's fine if they were cast aside by Papa, stating that as long as he's with them, he would be fine. He tells them that there are more to their lives than piloting.

Episode 17: Eden
Kokoro reads her baby book by the greenhouse. The 9's later arrive and they tell Squad 13 that they came to check on Papa's orders. They are to stay at Squad 13's boarding house for a while.

During the evening, 9'δ looks through the hallway when she almost bumps into Kokoro. She holds her before she falls and asks if she's okay. Kokoro thanks her and asks what she's doing. She says that she's exploring the place and asks that she doesn't tell the others. She agrees to and bows after saying goodnight. On the ground, Delta notices Kokoro's baby handbook. Delta shows this to the other Nines and 9'α notes that it covers things that Papa hadn't taught anyone. Kokoro smiles as she plays with her doll in one of the abandoned rooms.

The following day, Kokoro brushes Mitsuru's hair in the greenhouse. She says that, since the Nines are there, someone should be coming to get them soon. Mitsuru says that he'll be a bit sad to leave since they only began spending time together after he came there. This makes Kokoro happy and begins patting his head. She slides her hand down the nape of his neck, much to his confusion. She says that his body is much tougher than a girl's. She rubs his chest and says that boys and girls have such different bodies, and there's a reason for it. Mitsuru is confused and Kokoro explains that she read that boys and girls can create new life by joining their bodies together. As she unzips his uniform, she says that she thinks that it represents hope for them. He shoves her hand away and stands, asking what she's doing.

Before she can explain, Zorome asks if they just tried to stick their bodies together and if they're imitating Hiro and Zero Two. Mitsuru zips up his uniform and asks if he needed something. He says that he was supposed to be on water duty, to which Mitsuru quickly says that he will. After Zorome stomps off, Mitsuru asks why she did that out of nowhere. Kokoro says she'd been thinking about it for a long time.

Later when Hiro and Mitsuru enter the living room, Miku says that he's there. Smiling, Ichigo says that Zorome told them about him and Kokoro. Futoshi suddenly grabs Mitsuru's collar and asks if they'd kissed. Kokoro looks down and blushes, and they realize they had. They are interrupted by the Nines entering the room.

9'α holds up the childbirth handbook and asks if they recognize it. With Kokoro and Mitsuru's reaction, he says that they do. He asks for an explanation from Kokoro since she's the one who dropped it. He says that it's strange, since it wouldn't have been provided in the study there, and it definitely doesn't belong to her. Kokoro apologizes for not telling them all. She turns to her squad and says she wants to make a baby. This confuses the other parasites and 9'α mockingly says that Papa had banned that. Goro asks Mitsuru if she said anything, and he fidgets uncomfortably.

Kokoro turns back to the Nines and asks if it's so bad since it's how all humans were born. Futoshi asks if Papa didn't create them and Kokoro explains that they were born like any other animal and it had always been like that for all living things. She says that she wants to leave something behind before she's gone and, turning to look at Mitsuru, she happily explains that their purpose in life isn't just to ride FRANXX; they could also carry new lives and leave them for the future. When she says that it made her happy to hear that, she is interrupted by 9'a calling her disgusting. When she turns to him, he says that she's disgusting. He explains that humans have evolved and cast their reproductive functions aside in the process. Reject that, and they all have to go back to conforming to one gender. He asks if gender isn't just a pain that's tolerated to operate the FRANXX. Kokoro has tears in her eyes and Mitsuru begins to say something, but Ikuno suddenly walks up and slaps him. Alpha then mocks Ikuno for her actions in being ruled by her actions and before she can attack him again, she is pulled back by Goro and Ichigo. Nana and Hachi appear and ask them to stop.

Kokoro is taken in to talk with Hachi and Nana. Nana exclaims that the recent event is why she didn't want to let the Nines in. Hachi says that Papa sent them, so they couldn't just turn them away. She says that they should put an end to their test now to which Kokoro asks what she means. Hachi says that it was on Dr. FRANXX's orders that they didn't contact them over the past month and that it would be their final test. Though they still monitored them, and know what she was trying to do with Mitsuru. In regards to Kokoro wanting to have a baby, Nana says that no one can speak of that, let alone do it. When Kokoro asks why they have organs for reproduction, Nana says to pilot the FRANXX. She is taken aback but then asks what her feelings are for then, and Nana has a blurred flashback and then swipes at Kokoro before clutching her head as she tells her to be quiet. Hachi orders Kokoro to return to her dorm and they'll give her her orders in time and she runs out of the room.

Mitsuru sits in the greenhouse pondering about what to do, and he later determinedly leaves the greenhouse and goes to one of the abandoned rooms, where he finds her crying on one of the beds. She says she was wrong and apologizes for trying to force him to go along with it. He tells her not to and says she wasn't forcing him to do anything. She says he's lying and tells him not to try and be nice and asks him to leave her alone. As she walks out, he grabs her arm and refuses. He pulls her into a hug and asks for her to lean on him more because he wants to make her happy. She asks if it is so bad to create a new life and if they aren't allowed to think about the future. He kisses her and she pulls him closer to her. They finally consummate their relationship and lay in bed together.

Episode 18: When the Sakura Blooms
Mitsuru wakes up after spending the night with Kokoro again. They look out the window together where sakura petals float in the wind. He says it's beautiful and she agrees.

Hiro explains to the parasites that he wants to have a wedding. As they don't know what it is, Hiro explains that it is a ceremony where two people vow to always be together, and he says that Kokoro and Mitsuru will marry at this wedding. Kokoro and Mitsuru express how they really liked the idea and that they decided to do it before leaving Mistilteinn. Everyone voices their support, though they stop to check on Futoshi. While Kokoro tries to say something to him, Futoshi exclaims that he wants to play the priest so he can be right beside Kokoro and Mitsuru to congratulate them. Kokoro thanks him. Zero Two shows Kokoro a drawing of a wedding dress and she asks what material they can use to make it. Miku and Ichigo collect curtains to do so and the girls make Kokoro's wedding dress together. Elsewhere, Mitsuru makes rings for the wedding ceremony and hopes that Kokoro will like them. The parasites later paint and decorate their house and they all later pose for a picture.

The next day, Mitsuru paces at the bottom of the stairs. Kokoro comes down in her wedding dress and Mitsuru is clearly amazed by her, though he quickly becomes flustered and looks away. She takes his hand and says they'll find happiness together and he agrees and smiles. They then begin the ceremony, being congratulated by their friends who throw sakura petals as the two walks. After saying their vows, Futoshi tells the couple to exchange rings. After they do, Futoshi tells them to kiss. Before they can, they are interrupted by APE SP who tell them to freeze. Mitsuru and Kokoro attempt to escape but are stopped by the Nines. Alpha tells them that Papa said they were dangerous and need to be re-indoctrinated. Zero Two tries to protect them, but the other Nines are able to defeat her. APE then takes Mitsuru and Kokoro and tear them from each other. Kokoro screams out for Mitsuru and cries.

Weeks later at the Bird Nest, the squad is reunited with Kokoro and Mitsuru but they are devastated to find out the two not only do t remember the wedding but they also don’t recognize each other because their memories have been altered. Kokoro later walks through a hall and appears to see a sakura tree, though it is actually a fragmented memory she had with Mitsuru. She then looks at her ring.

Episode 19: Inhumanity
Futoshi shouts at Kokoro and says that she isn't changing his mind and storms off. Mitsuru asks what they were talking about, and she says he doesn't want to be her partner anymore and that he'll team up with Ikuno and he wants her to team up with Mitsuru. They're both confused, and Mitsuru says that they keep telling them all this stuff that happened between them, but neither of them remembers anything. He says he doesn't believe he'll develop feelings for her and she agrees. Goro says that Mitsuru and Kokoro were implanted with fake memories. Ichigo wonders if their memories are lost forever. Futoshi asks if what they did warranted their memories being erased. Hiro asks Papa that Misturu and Kokoro's memories be returned. Papa refuses and says that they removed the unnecessary information and there is no way to return them. Hiro says that they took away Zero Two and his precious memories as well as Kokoro and Mitsuru's. He says they can't see him as their Papa and to set them free once the battle is over. Papa agrees, as long as they fulfill their duties in the next mission.

Episode 20: A New World
Nana's replacement explains to the parasites that the Star Entity is now under their control and they'll be booting it up the next day. The FRANXX squads are tasked with keeping all enemies away from it.

Futoshi tells Goro that both Kokoro and Mitsuru took off their rings. Kokoro suddenly spills her water and runs to the bathroom to throw up. Miku, Ichigo, and Ikuno follow her and Ikuno says that it'd been happening a lot lately. Ichigo says maybe she shouldn't go along with the upcoming mission. She says she must for Papa, even if it would cost her life. Miku hugs her and says that none of them belongs to Papa and they have to leave their mark on the future, just like she said.

After the Parasite assembly, the 9's mock Squad 13. Zero Two steps forward and says they're all stronger than them since they have their eyes on the future. This shocks Kokoro especially.

An announcer says that a klaxosaur pack is headed towards Gran Crevasse. The parasites all head out. Kokoro rubs her ring finger and Mitsuru says that since they were partners before, they should be able to connect. At the Gran Crevasse ruins, the FRANXX attack the klaxosaur. When Mitsuru compliments Kokoro, he initially calls her by her code number but then has a pain in his head when saying her name. Genista struggles and Kokoro gets the same pain when saying "Mitsuru." While they are unable to fight, they are supported and defended by their teammates. However, they soon manage to return to the battle.

Episode 21: For You, My Love
The squad is confused about who they are supposed to fight but Kokoro doesn’t care because she feels obligated to keep fighting, which concerns Mitsuru. They decide to return to the Gran Crevasse to find out themselves but are confronted by the 9’s for disobeying Papa’s orders. VIRM kills two of the 9’s and the squad resumes towards its destination. Although Kokoro hesitates, Mitsuru asks her to keep going and she agrees.

Squad 13 helps Zero Two so she can go and save Hiro. The corridor is blocked off and VIRM soldiers accost them. Ikuno and Futoshi clear a path and let Zero Two go alone with Ichigo and Goro. Kokoro decides to stay behind to protect the others and to defeat the VIRM enemies, even though it might cost her life. Mitsuru is clearly worried but before he can say anything, Miku announces that she and Zorome will also stay behind helping them. Mitsuru agrees that they all should work together and although Kokoro is hesitant, she agrees.

Episode 22: Stargazers
Squad 13 works together to attempt to harvest crops to eat due to the limited amount of rations left. During a meeting, Miku credits Kokoro for her knowledge on plants but she says it’s nothing. Kokoro then becomes nauseous and leaves to go rest while Mitsuru attempts to follow her but stops himself. While working in the fields and seeing more klaxosaurs leave to fight VIRM, Kokoro suffers from nausea again and collapses. As she drifts in and out of consciousness, she sees Mitsuru reaching out for her, holding his head in his hand and calling out to her. In the infirmary, the new Nana tells Kokoro she is pregnant. Kokoro is confused about what ‘pregnancy’ means. After being explained what it is, Kokoro is shocked and then she is distraught as the new Nana explains a pregnant pistil cannot pilot a FRANXX. She gives Kokoro the choice of having an abortion or gives birth before leaving the room. Mitsuru falls to the ground in shock as he realizes he has fathered her unborn child. Kokoro frantically begs the new Nana for an answer on what she should do before Miku comforts her and sends the boys out of the room.

Kokoro keeps to herself in her room holding her stomach, as she struggles with what to do. Mitsuru tries to see her but he is unable to bring himself to do so.

When Squad 13 gets ready to leave to go after Zero Two, Kokoro and Mitsuru stay behind because her pregnancy makes her incapable of piloting FRANXX.

Episode 23: DARLING in the FRANXX
As the other parasites leave for space, Kokoro remembers when Mitsuru told Hiro he would be staying behind and Hiro said he understood because Mitsuru wanted to reconcile with her, which surprised her. Kokoro asks Mitsuru why he stayed behind because he could’ve gone with another partner and he says he wanted to because it’s his responsibility. Kokoro says she doesn’t expect anything from him because they don’t remember.

Kokoro tends to Zero Two as new injuries start emerging on her body and she tries to stop Zero Two from walking away. Kokoro starts to feel hopeless because she is not a parasite anymore and she rubs her stomach.

The effects of the battle create a severe thunderstorm and Kokoro tries shielding Zero Two. Mitsuru orders her to get inside but she refuses because she wants to protect Zero Two. Mitsuru says it will be bad for her body but Kokoro breaks down that she is no longer a parasite and has nothing left to live for but the least she can do is protect Zero Two. To her surprise, Mitsuru says he will stay with them. She pleads with him to leave her alone and he doesn’t have to feel responsible but he insists he is not trying to be responsible and if she has nothing, then neither does he. However, he has found a reason to live: to protect Kokoro and their baby. He shows her his wedding ring and Kokoro asks why he still has it and why he still calls her by her name even though it hurts him. He tells her that even if they don’t have their memories, they can start all over again and he will call her by her name as much as he wants. Kokoro shows she still has her wedding ring and cryingly calls out to Mitsuru. They are then seen crying together as he hugs her.

When the storm passes, Kokoro and Mitsuru watch Zero Two suddenly smile and her body turns into a statue. They are then seen holding hands and wearing their wedding rings.

Episode 24: Never Let Me Go
Kokoro enters the third month of her pregnancy and her stomach is shown to have gotten bigger. The new Nana makes arrangements to get her pregnancy clothes and have her monitored because she is the first parasite to bear a child. Kokoro requests she receives no special treatment but the new Nana insists because, as the first pregnant parasite, Kokoro must set a precedent for the others. Later, while Kokoro teaches some of the girls how to sew, Mitsuru interrupts and asks her if she needs him to do anything, but she assures him she will be fine. Futoshi and Zorome run to Kokoro and offer the food they say is full of good nutrients, and she thanks them. They then get ready to head back to the fields and have to drag Mitsuru, who is reluctant to leave Kokoro's side.

245 days since the gate passage, Kokoro gives birth to a baby girl. Mitsuru rushes to her hospital room and cries when he sees his daughter. Kokoro asks the baby to call Mitsuru “papa”. They name their daughter Ai, a name Mitsuru chose because it means ‘love’, a word they were never taught but learned from Hiro and Zero Two. Kokoro spends her time taking care of Ai and helping with day to day chores.

Two years later, Kokoro and Ai meet with Futoshi, and Kokoro tries to teach Ai to call him ‘Uncle Futoshi’. He tells her that he is planning to leave the Bird Nest to pursue his new dream of becoming a baker so he can make delicious bread for the new children. Kokoro compliments him and sadly thanks him for being there for her when she felt she couldn’t do anything for him as a partner. He tells her to smile and he also thanks her because she helped him grow up. Shortly after, while playing in the field, Ai looks at Zero Two’s statue and begins saying “Darling”. Her parents hear this and alert everyone, who hold hands and send their thoughts to Hiro and Zero Two. Kokoro and Mitsuru say they chose the name Ai for their daughter because it means ‘love’ and, although they never knew the word because they were never taught about it, they learned its meaning from Hiro and Zero Two. After Hiro and Zero Two sacrifice themselves to destroy the VIRM home planet, Kokoro breaks down in tears and mourns the loss of her two friends but she thanks Hiro and Zero Two for saving their planet. Ai comforts Kokoro, who hugs her, and Mitsuru comforts her, too. At some point afterward, Kokoro gives birth to her and Mitsuru’s second child, which is a boy.

Eight years pass and Kokoro attends a school ceremony with Mitsuru and it is revealed they have three children and they are expecting their fourth child. The former Squad 13 later reunites at a cherry blossom tree that had grown from Zero Two’s ashes and they thank Hiro and Zero Two, speaking of the lessons they have learned from them.

Mitsuru
Kokoro is the first to notice that something is wrong with Mitsuru after he tried piloting with Zero Two out of desperation to prove he was better than Hiro and was left traumatized. From there on, they have random walk-ins with one another mainly inside the greenhouse. Despite his aloof demeanor, she offers him help and advice, but he refuses it and sees it as Kokoro is pitying him.

Starting from Episode 05, Kokoro exhibits a deep interest in Mitsuru to the point of finding an excuse to talk to him and initiating conversations with him. She offers to listen to whatever is bothering him and admits she admires him for being so tough and never leaning on others, but he rejects her and tells her to leave him alone. His grudge against Hiro causes Kokoro to worry about how this affects Mitsuru’s mentality.

During a vacation to the beach, the squad explores an abandoned city Mitsuru finds. He speaks harshly to Kokoro when she mentions how scary the cavern is but he says to everyone that he can't look after all of them. Nevertheless, he was the one to find Kokoro, who had wandered off on her own and save her from being injured from falling debris.

When the boys and girls start a "gender conflict" due to the events of Episode 08, Kokoro finds Mitsuru in the greenhouse and she proceeds to tell him the names and meanings of the plants. She then wonders if he has no problem talking to her because of the fight between the boys and girls, but he calls it stupid and he wants nothing to do with it. She praises him for his honesty and he is brave to speak out his opinion. He then finds she kept the baby book she found but tells her it has nothing to do with him, confirming she doesn’t have to worry about him revealing its existence although this is considered a violation of regulations.

Kokoro shows deep concern for Mitsuru when she learns he underwent a risky procedure to become a parasite. Driven by a determination to help him with his problems, she goes as far as to break her promise with Futoshi and become Mitsuru's partner. When they rendezvous in the greenhouse, Kokoro asks him why he thinks humans stopped having children because having a baby seemed to be the most natural thing in the past. He tells her not to think of unnecessary things and asks her if she chose to be his partner out of pity but she denies this. During the battle, Mitsuru shuts down Genista and says he is incompetent but Kokoro denies this and convinces him to confess that his grudge against Hiro over a broken promise has led him unable to trust others. Kokoro sympathizes with him because she broke a promise to Futoshi but, to prove she trusts Mitsuru, she risks her life to pilot Genista. Mitsuru stops her and asks her how she can trust him so much, and she smiles in response. Mitsuru also smiles and calls her ‘unbelievable‘. She later is shown to be surprised when Mitsuru promises to Futoshi that he will protect Kokoro from now on.

As they spend more time together, they develop a strong bond of trust and affection. Mitsuru goes to the greenhouse and asks Kokoro to cut his hair. She is confused because the request came out of nowhere but she merrily agrees after seeing his awkwardness. As she cuts his hair, he confesses how guilty he feels for how badly he treated Hiro for something that wasn’t his fault and he now believes he used his grudge to give himself a drive, but without it, he now has nothing. Kokoro praises him for resolving the misunderstanding and he compliments her handiwork. In response, Kokoro suddenly kisses him, which surprises him and she is deeply embarrassed for having done it out impulse and runs away. However, the two work together to make a salad for dinner and smile at each other when they are praised for their joint effort.

Shortly after, Kokoro brushes Mitsuru‘s hair in the greenhouse after learning they will be leaving Miltisteinn soon. Both express their sadness of leaving but Mitsuru says it makes him sad because they have just gotten to spend time together. Due to her growing feelings for Mitsuru and her desire to bear a child, Kokoro suddenly talks about how boys and girls are able to create a new life while she tries to initiate sex with him. He is deeply confused and rebuffs her. Afterward, After her book is found by the 9’s, Kokoro confesses her yearning to have a baby and she now believes they can live a life other than piloting the FRANXX while smiling and looking at Mitsuru. Later that night, Mitsuru finds Kokoro in one of the abandoned rooms after being berates by Alpha and comforts her. This leads to a passionate kiss and they have sex for the first time. They begin secretly meeting in one of the abandoned rooms to spend their nights together.

Kokoro and Mitsuru later decide to get married after learning the meaning of marriage from Hiro. However, the 9’s inform Papa of this and the two are detained and taken away in the middle of their wedding. A couple of weeks later, they are returned to the squad but have no recollection of each other and the wedding, as their memories have been altered. Kokoro, however, has a brief recollection of a sakura tree from a fragmented memory she shared with Mitsuru.

Kokoro attempts to become partners with Futoshi again but he refuses and insists she stay with Mitsuru. Both are confused and Mitsuru says everyone is telling them about the things that happened between them but they don’t remember anything. Mitsuru also says he doesn’t believe he will ever have those feelings for her and she agrees.

The two then take off their wedding rings. While Futoshi and Goro are talking about this, Kokoro suddenly becomes sick due to morning sickness, tossing her cup of water to the floor, and rushes to a nearby bathroom. Ichigo and the others look on in sorrow as Kokoro tries to explain how she will continue to fight for Papa regardless. Later in the episode, despite wanting nothing to do with each other, Mitsuru and Kokoro decide to pilot together, and they do a very well job at the beginning of the battle. However, while giving a compliment to Kokoro, he accidentally calls her by her nickname (“Kokoro”) and triggers a memory as a painful flash. She asks what is wrong calls him “Mitsuru”, which triggers a painful flash for her too. With no recollection of the past, the two are fear-stricken and shut down their FRANXX in the middle of the fight, forcing Ichigo to come to their aid and protect them. They do not continue in the fight afterward.

A few days later, Kokoro finds out she is pregnant with Mitsuru’s child. Faced with the choice of having an abortion or keeping the baby, she is left feeling distraught on having lost her ability as a pistil and she is paralyzed with fear of what she should do. Mitsuru is so shocked by the news he falls to the ground and later expresses his own dilemma on what he should do. He tries to see Kokoro as she ponders this alone but he still doesn’t know what to do. Because Kokoro is unable to pilot a Franxx due to her pregnancy, she and Mitsuru don’t accompany the rest of Squad 13 to help Hiro save Zero Two while she is subconsciously battling the VIRM.

Kokoro is confused about why Mitsuru chooses to stay with her rather than go with the squad to space and questions him about it. But his response about the baby being his responsibility as well dissatisfies her. She makes it known to Mitsuru that she doesn’t expect anything from him due to their memory loss despite his insistence that he wants to support her. Kokoro further rejects Mitsuru when he tries to get her out of the storm and she confesses that she believes she has no purpose in life now that she is not a parasite anymore and she will risk her life to protect Zero Two. Mitsuru decides to stay with her but she pleads with him to leave her alone and she doesn’t hold him responsible for the baby. He retorts he is not trying to be responsible but he wants to protect her and their baby has given him a reason to live. After telling her he wants to start over with her and they can find what love means together, he shows her his ring. Kokoro cries and shows her ring, and they embrace as they cry together. They are later seen holding hands and wearing their wedding rings.

When Kokoro starts to show in her pregnancy by the third month, Mitsuru becomes overly protective of her and tries to be as attentive to her as much as possible. Although Kokoro warms up to Mitsuru and appreciates him, she tells him that he worries too much. As her pregnancy progresses, Kokoro and Mitsuru start to become excited at the imminent birth of their child. When Kokoro gives birth to a girl named Ai, Mitsuru cries out of joy and Kokoro smiles happily at him, and they gradually grow closer together as they raise their daughter. After two years, they are shown to have grown to deeply love each other as they tell Hiro and Zero Two about Ai. After ten years of marriage, they are shown to still be happily married and they have three children with a fourth child on the way.

Futoshi
Futoshi was Kokoro’s first partner upon being assigned to Squad 13. She gets along exceedingly well with Futoshi. She frequently comforts and compliments him. During their first time in Genista, they flash each other a thumbs up in the cockpit before beginning, and they prove to be compatible when they successfully synchronized during their startup ritual. Kokoro reassures him he did a good job as they take their first steps.

They seem to have, as Zorome describes, a "lovey-dovey" relationship. In Episode 05, Kokoro offers Futoshi the seat next to her when Zero Two takes his spot, and she then hand-feeds him toast, imitating what Zero Two is doing to Hiro. Futoshi is shown to be very devoted and protective of Kokoro, to the point he reprimands Mitsuru for talking coldly to her and willing to risk his own life to protect her. While Kokoro is grateful for his kindness, she is secretly uncomfortable with his feelings, especially when she was shown to be embarrassed when he declared he wasn’t ogling her when the girls’ parasites melted in front of the boys because he thought she was beautiful.

By Episode 11, their friendship hits a rough point. When Futoshi vowed to always protect her and he asked Kokoro to be his partner forever, she was noticeably uncomfortable but agreed. Later, an offer to switch partners leads her to break their promise and switching partners in favor of Mitsuru, devastating Futoshi and she apologizes. Kokoro initially seemed to be content with the switch but she later admits to Mitsuru about feeling bad about it because she hurt Futoshi and tells Mitsuru that she thinks of herself as a bad person for having done it, and she wouldn't expect to be forgiven.

However, Futoshi never blames Kokoro for breaking their partnership and his only concern was that Mitsuru took her safety into consideration. After Mitsuru vows to protect her, Futoshi admits he loved her. They quickly patched things up and remain friendly, so much so that Futoshi shows his full support for Kokoro and Mitsuru’s relationship when they make it known, despite the initial surprise and sadness, because he only wants them to be happy. Afterward, he even presided over their wedding and was the most enraged at Papa for erasing their memories. Kokoro attempted to partner with Futoshi again but he refused and insisted that she srmtau with Mitsuru. He later congratulated them after their daughter’s birth. Kokoro further insists that her children call Futoshi ‘Uncle Futoshi’, symbolizing their strong friendship.

Miku
Kokoro and Miku have been best friends since childhood, and both recall a moment from their days in the Garden in which Miku made a flower crown for Kokoro. Although their personalities are complete opposites, they get along better with each other and Kokoro seems to be the only girl of the squad who can reason with Miku in problems. While they maintain a close friendship, Kokoro is not completely honest with her, such as her desire to have a child and the possibility of living a life beyond piloting the FRANXX. Miku is surprised to learn Kokoro kept her true thoughts a secret from her but is supportive of her nevertheless. So much so that, after Kokoro’s memories, are altered and she is willing to die for Papa, Miku cries and tells her none of them to belong to him and it was Kokoro who taught the squad they have to leave their mark for the future. Upon reaching adulthood, they remain close.

Children
Kokoro has three children (two daughters and one son) with Mitsuru and, by the end of episode 24, is revealed to be pregnant with their fourth child. Kokoro is shown to be a loving mother towards her children.

Ai is Kokoro and Mitsuru’s first child and eldest daughter. Before becoming pregnant, Kokoro yearned to bear a child to leave a mark for the future but she loses this desire when her memories are altered. She was shocked to find out she was pregnant and distraught over whether to have an abortion or give birth, especially that keeping the baby would mean the end of her ability to pilot the FRANXX. With Mitsuru’s support for her to keep the baby, Kokoro later developed a new purpose in life by raising her child and decided to keep the baby. Thus, she came to love her child and, when Ai was born, Kokoro was happy and became a loving mother to her daughter.

Their second child is a boy, who is born shortly after Hiro and Zero Two’s deaths and he takes after Kokoro in looks. Their third child is another girl, who appears to be a toddler and greatly resembles Mitsuru. By the ten-year time skip, they announce they are having their fourth child.

Hiro
Kokoro was friendly with Hiro and worried about him when he initially failed to become a parasite. She commented she would be said if he was sent back to the Garden and they would never see him again. Although she was cautious about Zero Two due to the dark rumors about her when Hiro began piloting with her, Kokoro was glad to see how Hiro had begun to smile and laugh after meeting Zero Two, as she notes she hasn’t seen him so happy in a long time. She considers him as a dear friend and enjoys being on the same team as him. When Kokoro was about to give birth, Hiro was worried about her and the baby but believed she would be alright. When Hiro sacrificed himself to save everyone, Kokoro was saddened but truly grateful for his selfless act.

Zero Two
Initially, Kokoro was wary of Zero Two due to the rumors surrounding her as the ‘Partner Killer’, and how she tends to push Hiro to his limits. Kokoro was further confused by Zero Two’s rebellious and unusual behavior, especially her flirtation with Hiro. However, as she got to know her, Kokoro grew to accept her as a comrade and later as a true friend and learned to look past Zero Two’s dark past because of her positive influence on Hiro and she has saved their lives many times. Further demonstration to Kokoro’s friendship with Zero Two is when Zero Two helps make a wedding dress for Kokoro and when Kokoro refuses to leave a catatonic Zero Two during a thunderstorm. When Kokoro was about to give birth, Zero Two was confident Kokoro would be alright. Later, Kokoro mourned Zero Two’s death and was grateful for her sacrifice to save everyone.

Etymology
Kokoro's nickname may use some of the numeral's readings from her real name "Code:556": ko, an alternative spelling of "5" and ro as in 6. Kokoro is also the Japanese word for "heart", reflecting Kokoro's caring and kindhearted personality.

Quotes
"I believe in you, Mitsuru."

- Kokoro

"We lived our lives believing our only purpose was to ride the FRANXX into battle. But you know what? That might not be true! We could carry new lives and leave them for the future. When I learned about that, I was very happy"

- Episode 17; Kokoro says this to Squad 13 and the 9's

Trivia

 * The name Kokoro means "heart, mind, soul" (心).


 * Kokoro is shown to be skilled in sewing, asking for a sewing kit for her annual present from Papa and making a baby doll with it. She later passes this doll on to her children.
 * She enjoys gardening and is knowledgeable in horticulture, as she tends to the greenhouse of Mistilteinn, provided the parasites instructions on how to grow crops and made a salad from edible flowers.
 * Kokoro is the first parasite to naturally conceive and give birth to a child.
 * Kokoro's codename "556" and Mitsuru’s codename "326" when added together, equals 882, which can be read as "hahani", which means “to become a mother”. it can also be read as “papani”, which means ”to become a father” since “ha” and “pa” have the same Japanese letter in Hiragana without a diacritic.
 * With a different kanji, “hahani” can also mean “rebellion”. The fact that Kokoro and Mitsuru consummate their relationship, get married, and have children is in defiance to Papa and APE. As well as the fact their memories were erased over violating the rules provokes their friends to rebel against Papa.
 * In addition to becoming the first human to have bore a child in close to a century, she is the youngest pistil to become a mother, as she became pregnant at age 14 years and 10 months, and gave birth to Ai at age 15 years and 7 months.

Кокоро