The distant future: Humanity established the mobile fort city, Plantation, upon the ruined wasteland. Within the city were pilot quarters, Mistilteinn, otherwise known as the “Birdcage.” That is where the children live... Their only mission in life was the fight. Their enemies are the mysterious giant organisms known as Kyoryu. The children operate robots known as FRANXX in order to face these still unseen enemies. Among them was a boy who was once called a child prodigy: Code number 016, Hiro. One day, a mysterious girl called Zero Two appears in front of Hiro. “I’ve found you, my Darling.”

Jinta Yadomi and his group of childhood friends have become estranged after a tragic accident split them apart. Now in their high school years, a sudden surprise forces each of them to confront their guilt over what happened that day and come to terms with the ghosts of their past.

A spy, an assassin and a telepath come together to pose as a family, each for their own reasons, while hiding their true identities from each other.