Raizo and Kiriko are raised by The Ozunu, an organization which trains orphans to become ninja assassins. They have a romance, but when Kiriko asks Raizo to escape from The Ozunu's control with her, he refused. Being considered as a betrayals, Kiriko is caught and executed in front of Raizo, which makes Raizo begin to harbor resentment and doubt towards the Ozunu. He goes against the order of Lord Ozunu and fight against his fellow ninja kin. After that, he escapes and try to intervene Ozuno assassination attempts.