Adult

Adults (オトナ,Otona) are the grown versions of humanity who reside in plantations. The Adult population resides in tall glittering skyscrapers at all times and rarely walk outside. Giant robots called FRANXX are piloted by children referred to as ‘parasites’, whose sole purpose in life is to protect adult-filled cities against the Klaxosaurs.

Appearance
Each adult usually wears a white headdress which covers their eyes and nose. Their skinis seldom exposed in the air. In Episode 01, a large population of adults from Thirteenth Plantation attended the ceremony. Their clothing is quite standardized (i.e. long garments). Some of them held a binoculars-like instrument during the ceremony.

In Episode 10, Old Man and Old Woman are two adults who live in the Inside City. The Old Woman also chats with Zorome for a while.

Overview
As immortals, the adults live in tall skyscrapers and rarely walk outside their residences. According to Dr. FRANXX, the adults became so tedium that they not only forgot about the existence of the Klaxosaurs but lost all sense in trivial matters, such as taste, smell, and emotion. They rely on technology to find fulfillment in these by receiving dosages of emotions from a brain rewarding system, which transmits these feelings to their brains while they sleep. Zero Two finds this way of life to be the equivalence to being dead, as none of the adults are willing to set foot out of their comfort zone to experience something trivial, like the sensation of ocean water or the taste of sweets.

The adults are aware of the existence of the parasites and are strongly hinted to have contributed their DNA material for Dr. FRANXX‘s cloning research to create the children. Concepts such procreation and relationships are considered obsolete and undesirable by the adults, as they find people leaning on others for support to be an annoyance and are deliberately kept segregated from the children, who are deemed “infectious” to them. Their bigoted perspective the children is explored more thoroughly in the manga; the mayor of Cerasus refers to the children as the “former humanity” and it makes him unpleasant to even speak to them let alone come into physical contact with them. When a child comes into contact with anything within the city, the area is heavily quarantined with bacterial spray to rid the area of “contamination” and “bacteria” that they believe is released from the children.

The adults do cohabite in male and female pairs but not because of intimacy or commitment; they do so because it is a traditional custom since ancient times, though they rarely if ever communicate with each other and lead separate lifestyles. They are aware of how adults previously lived together and participated in other customs, such as marriage and procreation but they find these customs to be an annoyance and a burden. This reflects their egoism, as immortals, of superiority compared to not only the children but the people who existed prior to the discovery of immortality.

The adults seem to be physically reliant on magma energy, as seen with the Old Woman who sprays her apartment with orange-colored disinfectant and has an orange heart attached to her. They wear a heart presumably containing magma energy on their chest area. It is unknown how they interact, with the exception of the old woman who treats Zorome with kindness and looks after him when he got lost in the city. They lack sentimentality and common sense in interpersonal relationships. They also seem to share an physiology different than the children, as the old woman had to use pet mode settings to treat Zorome’s injuries and she gets sick from breathing the air in his presence.

History
After the discovery of magma energy in 2025, the development of human civilization accelerated and Dr. FRANXX discovered immortality could be achieved. Initially, only the wealthy could afford this but it later became universally available. By 2035, 70% of the human population became immortal but they lost their procreative abilities. To prevent a population explosion, APE passed a law heavily taxing childbirth among the mortals, causing a drastic decline in the birth rate. Due to an increase of klaxosaur attacks, APE led the proposal and construction of plantations, abandoning Earth’s surface. The immortals living in the cities of the plantations became known as ‘the adults’ by the parasites and were kept segregated from the children.

Episode 01
The adults of Plantation 13 attend the graduation ceremony of Squad 13 and watch the parasites closely as Papa presents his speech. Zorome and Futoshi are amazed that so many adults came to see them.

Episode 10
Zorome gets lost in the city after attending an award ceremony and is rescued by the Old Woman. After chatting, Zorome discovers the Old Woman lives with her partner but has no sense of content with trivial things, such as taste and sound. Zorome senses she is familiar to him but she denies they have met earlier. He asks her if they can be friends but she doesn’t answer as he is returned to Mistilteinn.

Episode 15
A super Lehmann-class klaxosaur smashes into Cerasus and sends a horde of Conrad-class klaxosaurs through the hole. Squad 13 fights against the Conrad-class klaxosaurs and manage to defeat the super Lehmann-class klaxosaur with Strelizia's aid. Before Strelizia can destroy the klaxosaur's core, a large klaxosaur hand emerges from the surface and crushes Cerasus, presumably killing off most of the plantation's adult population.

Episode 21
Papa and the Vice Chairman reveal themselves as the leaders of VIRM and begin consuming the souls of all the remaining adults of the plantations. Only the parasites' caregivers survive as the last immortal adults.