Living on Gui Cheng Island, called "the most dangerous city in the universe," is no easy task. Genetic doping is common for gangs to gain ultimate power. Shizuka, a young girl, 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!