Nao grew up in an ordinary household, experiencing her first love and first time during high school. After graduating from junior college, she got a job and later married her boyfriend. As a full-time housewife, she lived a calm and stable life, but over time her relationship with her husband grew stagnant, and sex became nearly nonexistent. Then, through a part-time job, she met a housewife friend who encouraged her to meet a casual sex partner. Hesitant at first, Nao couldn't bring herself to refuse and eventually agreed to meet the man. That encounter became the beginning of a major turning point in her life.