Sai, a career woman working at a major corporation, is well-liked within the company and always wears a smile, leading others to think she is a calm person. However, she has an immense sex drive and cannot maintain her sense of self without masturbating. Years of self-induced brainwashing have created a monster of insatiable desire within her. Suddenly, her junior colleague Himari, having missed the last train, barges into Sai's place and ends up staying over half-forcibly… Unable to masturbate due to the sudden unplanned cohabitation and abstinence, Sai gradually loses her rationality and begins to masturbate using her junior's belongings…
