Sumire grew up in a wealthy family and attended a school known as a girls' school. Although she was raised as a sheltered girl, she was precocious with men from a young age, losing her virginity in her first year of high school, and by the time she graduated from university, she had had sex with around 10 men. After some time, through an arranged marriage, she married a man five years older than her who worked for a top company. When she realized that her husband's sex life was lackluster, Sumire searched for a man who would not have an impact on her family life. A long time ago, she dated a sadistic older man for a while, but after having a child, they had not had sex for a long time.