Koutarou arrives in Yuunagi City, in order to enter the service of the Kuzuryuu yakuza family. A slender young man with an apparently innocent manner, he reveals the other side of his nature during a rather abrupt test from his new 'owner', his cold eyes promising death. He is there to replace his father as Izuna for Yuunagi City, claiming the lives of true villains at the orders of his new master.