Entering her 20th year of marriage, Momoko has been struggling with a sexless relationship with her husband. One day, she accidentally witnesses her daughter’s attempted sexual encounter, leaving her inwardly conflicted yet slightly envious. That night, her daughter’s boyfriend, Yuta, confides in her—he reveals that his penis is so large that he can’t penetrate her, and to her surprise, Momoko feels an unexpected curiosity. Gathering courage, she says, “Just the tip, okay?” and tentatively takes his cock inside her. Feeling vaginal pleasure for the first time in years, Momoko rediscovers the joy of being a woman. When Yuta advances on her again, all rationality vanishes, leaving only an overwhelming desire for pleasure.