Ranmaru, born half-human and half-monster, runs a small shop that handles whatever problems come through the door. A client arrives with a request: find a missing husband. When Ranmaru and his partner Raiou visit the client's home, they find a string of strange phenomena — people disappearing, others losing their minds, all of it connected to an old sword. The deeper Ranmaru investigates, the clearer it becomes that what is happening here goes far beyond a missing person case.