Infernal Weapons grant their wielders great power, but also have an evil spirit that possesses them. The few called Chrysalis can master them without becoming possessed, but they still slowly lose their humanity and transform into pure violent beings called Busoma. The secretive Shoshidai gather and hide such weapons, but even its members are unable to always resist their powers. A dying mother gives her infant son, Gai Ogatas, the infernal sword Shiryu, and after reaching adulthood must somehow control it to prevent from getting possessed.
