A near future, where humans have been defeated by the parasites termed Gastrea. They have been exiled to a land that was small and reside in despair in terror. Inside This universe trapped in darkness-- Rentaro, a boy living near Tokyo and manhood of their"Civil Safety"--a company specializing in fighting the Gastrea--is traditionally accustomed to attaining dangerous tasks. His partner is a precocious young girl, Enju. They fight until a day, when they be given a special mission from the federal government. This top secret assignment is to stop the devastation of Tokyo... Set in a long run, this thrilling heroic-action narrative... starts now!