Black Bullet, Vol. 5 (light novel)

With the chaos of the Third Kanto Battle subsiding, peace is finally returning to the Tendo Civil Security Agency, and Rentaro, Kisara, Enju, and Tina are taking full advantage of the quiet. But when an old friend from Rentaro's childhood reappears, their bright days turn suddenly dark--and Rentaro finds himself imprisoned for a senseless murder. He plans a desperate escape, but his enemies keep coming, and they are like nothing he's ever fought before...