"W·A," later identified as "Wild Adapter," is the name of a dangerous drug which transforms its users into an animalistic state; the users exhibit superhuman strength and a berserker mentality until the drug causes his or her organs to explode, effectively killing them. The corpses left behind by W·A are covered in fur and sport cat-like claws. The police are baffled by W•A even as they investigate the remains of W·A users, and the Yakuza wants it. Two powerful rival yakuza groups, the Izumokai and the Toujougumi are fighting to figure out and gain control of the source of W·A, a task made harder by the fact that no user of W·A have managed to stay alive after consuming the drug.