As a young boy Naoto lost his mother and was sentenced to death by his own clan, the Kageyama clan. His grandfather Masato Himurura , a legendary warrior that many call Susano, gave up his title and place in the clan so he could save his grandson’s life. Now several years later Naoto lives in a world where mystical creatures , humans and monsters coexist. As he grew older he and his Step-sister , Mirai, had a pretty normal life as highschool student at day and … occasionally as monster hunters at night. His life was pretty easy until… a silver haired knight appeared in his life and turned it upside down.