Hisaki and Yasha are an odd pair of friends: Hisaki is quiet, distant, and possibly keeping secrets from everyone, while Yasha is loud, violent, and in serious need of anger management. As they try to deal with each other, they soon find that creatures are after them for something they know nothing about: a demon supposedly hiding within one of them.
Hisaki attacks Kuroi, only for Kuroi's samurai servant, Iizasa, to stop him. Kuroi mentions a gift for Hisaki from his brother, Nekura... but he must defeat Iizasa to get it.