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)
— Description from AniList community (anilist.co).
