In a battle against the klaxosaurs only the children, classified as parasites, are humanity s hope in this dying world. Fighting in mechanized suits known as FRANXX, parasites are grouped up in male and female pairs to face the monstrous creatures. Hiro was once a prodigy FRANXX pilot. But when he gives up the fight, he meets Zero Two, the girl with the horns, and finds a new reason to keep going.