In a devastated post-apocalyptic future, Earth is a desolate wasteland. Humanitys only remaining strongholds are mobile fortress cities called Plantations, defended by giant robots known as FRANXX, who drive back the massive predatory Klaxosaurs that now roam the land. Failed pilot Hiro would be out there fighting them if he hadnt screwed it all up. But a chance encounter with a mysterious horned girl is about to change the course of his life and his destiny piloting the FRANXX.