Raiko Shimizu is a 20-year-old samurai of the Shimizu clan. When he was fifteen, he single-handedly massacred his entire clan, with the exception of his sister Raimei. This action is vengeance against his uncle and his gang . After this, he joins the Grey Wolves. He chooses not to tell Raimei his motives behind the massacre to protect her innocence. This leads to a battle between the two.