They have a dream of flying into the open sky, but they are aware that this dream will never materialize.
The few survivors of a future Earth that has been mostly wrecked and in which much of human civilization has been eradicated built walking fortress cities known as "Plantations" to protect themselves and the few survivors of civilization. The children of the residents are housed in the "Birdcage," a training institution that is well-known. They are taught there to combat the enigmatic life forms that annihilated humanity without ever having touch with the outside world. As a result, the kids are taught how to control the enormous robots called "Franxx" and how to engage in combat in them because merely being a "Franxx" pilot is evidence of one's existence.
Hiro, code number 016, was previously thought of as a kid genius, but when he was unable to keep up with his teammates and was unable to pilot a "Franxx," his life became meaningless; in fact, it's almost as if he never existed. But one day, he is confronted by an enigmatic female. She goes by the moniker Zero Two and exclaims, "I found you, my darling," as light refractions play with the two gleaming horns on her forehead.
