Miroku is a slit-mouthed woman whose ear-to-ear smile strikes fear into the superstitious, but who would have thought she had a fiancé? Once an infamous urban legend, the self-proclaimed "Queen of Folklore" has found her existence threatened by the public's declining belief in her. She is also roped into a contractual marriage with 17-year-old Kouichi Sano, a member of a family responsible for the continued existence of the supernatural.

Miroku is unenthused by the arrangement and wishes to regain her notoriety through her own means. For this reason, Sano makes his fiancée a deal: if she can scare him once before he turns 18, he will end the engagement. Miroku concedes to these terms but is unsettled by Sano's proposed condition—where he must make her fall in love with him.