Tank Chair

Shizuka takes on the most dangerous of assassin jobs, but she's not the one doing the killing. Rather, it's her brother, Nagi, a strong assassin who took a bullet to protect his sister, leaving him in a comatose state and having to use a wheelchair. However, Shizuka has figured out the key to waking her brother up: he must be faced with killing intent! Thus begins a violent journey of recovery, battling the most dangerous foes!

(Source: Kodansha USA)