Ranmaru is young cop with a dark past. As one of the few survivors of a mindless slaughter in his apartment block, he joins a special unit called TOKKO to avenge his parents. On his first case, the already ghastly murder scene turns to one of terror, as the inhuman killers start to massacre the police. After being saved at the last minute by a secret unit named TOKKO who wield swords instead of guns, Ranmaru's mind is filled with questions and he is determined to find out the answers, no matter what it takes. What are these monsters, and why did they recognize him?