The events of the anime series "Darling in the FranXX" take place in the distant future. Humanity is almost destroyed, and the Earth is ruled by mysterious giant life forms called klaxosaurs. The remaining humans have devised a way to fight these monsters - they have developed enormous militarized robots called FranXX. However, only a synchronized duo - a boy and a girl - can pilot such a mechanism. Pilots are trained in a special elite school, and if one of them fails the exam, their partner is doomed to obscurity.