Mankind lives in a walled city made of Varanium Monoliths to protect against Gastrea, a parasitical virus. "Cursed Children", girls with Gastrea virus, have superhuman abilities.

Civil Securities fight Gastrea with an Initiator, a cursed child, and a Promoter. Rentarō Satomi and his Initiator Enju Aihara receive a secret mission to save Tokyo.