A close to future, the place people have been defeated by the viral parasites named Gastrea. They have been exiled right into a small territory and dwell in despair, side-by-side in terror. In this world trapped in darkness— Rentaro, a boy dwelling close to Tokyo and member of the “Civil Security”—a company specializing in preventing in opposition to the Gastrea—is used to conducting harmful duties. His companion is Enju, a precocious younger lady. They struggle because of their peculiar powers till in the future, after they obtain a particular task from the federal government. This prime secret mission is to forestall the destruction of Tokyo… Set in a close to future, this thrilling heroic-action story… begins now!