Klaxosaur (叫竜(きょりゅう), Kyoryuu) is a biological weapon created by the Klaxo Sapiens in DARLING in the FRANXX. They are the central antagonists for most of the series but later joins forces with humanity to defend Earth from VIRM.


Klaxosaurs often appear as dragon-shaped or dinosaur-shaped machines. Each Klaxosaur seen to date has armor of a black coloration and glowing blue highlights. They exhibit an instinctual attraction to magma energy, which they feed on.

According to Hiro, Klaxosaurs possess chemical compounds similar to the FRANXX. This is due to that the FRANXX units were designed from Klaxosaur skeletal remains.


Over sixty million years prior to the main storyline taking place, the Klaxo Sapiens were a highly intelligent and technological race living on Earth until the planet was invaded by VIRM. In exchange for sparing the Klaxo Sapiens from suffering pain and sorrow, the VIRM offered them to merge with them as a single life form. The Klaxo Sapiens refused and a massive war broke out, which lasted for several hundreds of years and costed a large number in casualties. Although the VIRM were larger in size, they were outnumbered by the Klaxk Sapiens’ use of technology and evolution; the long period of fighting drove them to gradually evolve but at the cost of their reproductive organs. They built the Klaxosaurs as defense arsenals with male and female pairs; the female would merge with the klaxosaur while the male would become the core and maintain the control manuals. Ultimately, the VIRM was forced to retreat and the Klaxo Sapiens, anticipating a future battle with VIRM, drove themselves into Earth’s core to recuperate and prepare for another battle.

However, a couple of VIRM escaped and, when the human race began to evolve, they disguised themselves as humans and took authority of the humans, forming the government function called APE and the leader VIRM becoming the leader of the government and humanity, referred to as ‘Papa’. In the year 2025, Papa ordered Dr. Franxx to develop a research project on magma energy and immortality, leading to the use of magma drilling and strengthening the economy and government. However, in the year 2037, the klaxosaurs, who had been feeding off of the magma energy for survival, began attacking the magma plants. This conflict leads to the creation of the FRANXX units and the use of Parasites as pilots to combat against the klaxosaurs. At some point, they became aware one humanoid klaxosaur survived, the klaxosaur princess, and built the Star Entity, a massive weapon to be used as a last resort against the klaxosaurs.

Dr. Franxx continued his research on the connection between magma energy and the klaxosaurs. He learns that the klaxosaurs have been residing in the planet’s core to use the energy as nourishment and food source, and would die f its core is lost; as shown in Episode 15, the core of a Klaxosaur contains what resembles to be a human in a fetal position. It was initially unknown if klaxosaurs were biologically capable of reproducing the same way as humans or interbreeding with humans; as Zero Two appears human but is revealed to possess klaxosaur blood and klaxosaur characteristics, such as horns and fangs.

In Episode 17, members of the Five Sages secretly meet with the klaxosaur princess to negotiate a peaceful surrender in exchange for ending the war. She refuses and kills them. In the final battle with the klaxosaurs, in episode 20, it is revealed that they are piloted by both a male and female Klaxo sapien. This confuses the parasites who had always been told klaxosaurs are large aliens, and it is further shown the klaxosaurs share intelligence and personality characteristics no different than humans. Papa and the Vice Chairman, realizing the princess intends to take control of the Star Entity to eliminate VIRM for good, are forced to reveal their true identities and send a large armada of VIRM to attack, and decide to detonate the planet in order to destroy the klaxosaurs. The parasites, especially Hiro and Zero Two, ten against Papa and join forces with the klaxosaurs to stop VIRM from destroying the planet. The princess initially takes control of Strelizia with an unwilling Hiro but she concedes after seeing only he and Zero Two are capable of saving the planet. The VIRM retreat and a galactic battle begins in space between the VIRM and klaxosaurs, with the parasites joining them and emerging victories. However, the VIRM escape to another solar system and retreat to their home planet. However, after the planet is destroyed by Hiro and Zero Two, the klaxosaurs returned to Earth and drove into the planet, becoming part of it and allowing it to prosper. It was surmised the klaxosaurs decided to let mankind keep residing on the planet and, in return, the humans vowed to never use magma energy again.


Klaxosaurs are categorized by their size. Each class is named after the discontinuities inside the Earth.

  • Conrad-class (コンラッド級): small Klaxosaurs. Even smaller than a FRANXX. Presents not much of a threat. They move quickly, rely on strength in numbers and can merge to create a bigger Klaxosaur.
  • Mohorovičić-class (モホロビチッチ級): medium-sized. Can pose a serious threat to the plantations if left unattended but otherwise harmless.
  • Gutenberg-class (グーテンベルク級): large, intimidating and demoralizing to look at. Their siege weapons are capable of destroying plantations. Requires a joint operation to defeat.
  • Super Lehmann-class (超レイマン級): gigantic Klaxosaurs, having at least the size of a plantation. They are to plantations what scissors are to paper and can withstand an entire plantation exploding in their face. Requires an army and a massive amount of effort to defeat.


Kyoryuu uses the kanji for scream and dragon.

Klaxosaur is a portmanteau of klaxon, which is a loud electric horn, and the suffix -saur, which is derived from the ancient Greek for lizard and identifies the genera of the extinct great reptiles, the dinosaurs.



STAMEN Hiro | Goro | Zorome | Futoshi | Mitsuru
PISTIL Zero Two | Ichigo | Miku | Kokoro | Ikuno
OTHER Naomi | Old Woman | 081 | 090 | 245 | 9'α | 9'β | 9'γ | 9'δ | 9'ε | 9'ζ | VIRM
APE Papa | Vice Chairman | Gorilla | Marmoset | Lemur | Baboon | Tarsier
Dr. FRANXX | Hachi | Nana
FRANXX Strelizia | Delphinium | Argentea | Genista | Chlorophytum | Standard | 9 Model
EPISODES 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12
13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24
CHAPTERS 01 | 02 | 03 | 04 | 05 | 06 | 07 | 08 | 09 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20
MUSIC KISS OF DEATH | Torikago | Manatsu no Setsuna | Beautiful World
Hitori | CÅGE | Vanquish | Escape | Darling
LOCATIONS Cerasus | Garden | Chrysanthemum | Gran Crevasse | Cosmos