The game's protagonist Raikoh Minamoto (based on Minamoto no Yorimitsu) was born into a clan of executioners under the emperor's command. Raikoh was given the order to kill his own father. He couldn't bring himself to do it, so he stole Soul Shrine, his clan's ancestral sword, and fled the capital city of Kyoto. Upon his departure, the seal separating the demon and human worlds was broken. Kyoto was all but leveled and a wave of demons appeared. Raikoh was almost killed by the flood of darkness, but a princess banished to the netherworld saved him and held him in a state between life and death. The princess gave him a new body in exchange for his services. She would allow him to repent for his sins as an assassin by saving the world from the demons unleashed upon it. Raikoh begins his quest to restore the seal and stop the one responsible for its collapse.