口が裂けても君には

Miroku Shikabane is the Kuchisake-onna of Japanese legend, a self-styled Queen of Folklore whose slit-mouthed grin once terrified anyone superstitious enough to believe in her. Belief has faded and her power with it, so she is signed into a contract marriage with seventeen-year-old Kouichi Sano, whose family exists to keep the supernatural going. Miroku wants out, and Sano offers terms: scare him once before he turns eighteen and the engagement ends, as long as he gets his own shot at making her fall for him.