A near future, where humans have been defeated by the viral parasites named Gastrea. They have been exiled into a small territory and live in despair, side by side with terror. In this world trapped in darkness— Rentaro, a boy living near Tokyo and member of the "Civil Security" – an organization specializing in fighting against the Gastrea – is used to accomplishing dangerous tasks. His partner is Enju, a precocious young girl. They fight thanks to their peculiar powers until one day, when they receive a special assignment from the government. This top secret mission is to prevent the destruction of Tokyo... Set in a near future, this thrilling heroic-action story... starts now! (Source: Baka-Tsuki)

The future–where a terrible battle against a parasitic virus called “Gastrea” has been fought, and lost. Humanity is cornered, and lives in despair. Rentaro and Enju face constant danger in their work as a team anti-Gastrea specialists known as “Civil Security.” If the daily fight against oblivion weren’t enough, they’ll soon face a threat that could destroy all of Tokyo… (Source: Yen Press)