The main character, Haganemaru, is rescued by a certain woman while eating and running at a dumpling shop. The woman's name was Princess Oe Byakuren, and she was the daughter of a feudal lord who died in a confrontation with a demon. While talking to Haganemaru about his father, the demon that killed his father appears from the tombstone and attacks them. Haganemaru confronts the demon, but the opponent is the owner of an immortal body that can be restored even if his head is cut off...