Miki Hirayama is a married Japanese woman experiencing a childless marriage due to her husband's infertility. This circumstance heightens her vulnerability to manipulation. She responds to a fake job posting at a school, falling into a trap orchestrated by Tomimatsu and Shigezo designed to recruit women into a "housewives sex club."

While waiting at the school with another woman, Sanae, Miki displays significant impatience, chain-smoking cigarettes. Her lack of children and dissatisfaction with her family life increase her susceptibility to coercion. Once Tomimatsu initiates his plan, she succumbs rapidly, becoming "wax in his hands."

Physically, Miki possesses brown hair reaching chest length and gray eyes. Her attire includes thigh-high stockings and a garter belt. She is an adult, though her specific age is not provided.