Tank Chair

Nagi was once a terrifyingly capable assassin until he took a bullet protecting his sister Shizuka, leaving him comatose and dependent on a wheelchair. Shizuka eventually discovers something bizarre: sufficiently intense killing intent directed at her brother can briefly awaken the instincts buried inside him.

Determined to bring him back, Shizuka begins accepting the most dangerous assassination jobs she can find, placing Nagi before enemies hostile enough to force a response. Recovery becomes a violent procession of battles in which every opponent might be another step toward restoring Nagi, or the one threat that prevents him from ever returning at all.