In a future where humanity's survival hinges on battling giant Klaxosaurs, individuals seek refuge in fortified cities known as Plantations. Here, youngsters are trained to operate FranXX, enormous mechas crucial in combating these beasts. Hiro, a hopeful FranXX pilot, grapples with self-doubt after a setback. During a chance encounter with the enigmatic Zero Two, a feared pilot labeled the 'Partner Killer,' Hiro's world shifts. As they join forces against a Klaxosaur threat, Hiro discovers a new purpose but risks unknown consequences. Together, they navigate a dangerous path where redemption and sacrifice intertwine.