In a world plagued by creatures known as Kaiju, Kafka Hibino aspires to enlist in the Defense Force. He vows to enlist with his childhood friend, Mina Ashiro, but life takes them on different paths. While employed to clean up after Kaiju battles, Kafka meets Reno Ichikawa. Reno's determination to join the Defense Force rekindles Kafka's promise to join Mina and protect humanity.