Black Bullet

The world has already ended. The future—where a terrible battle against a parasitic virus called "Gastrea" has been fought...and lost. Humanity is cornered and lives in despair. Rentarou and Enju face constant danger in their work as a team of anti-Gastrea specialists known as "civil security officers." As if the daily fight against oblivion weren't enough, they'll soon face a threat that could destroy all of Tokyo...

(Source: Yen Press)