After marriage and childbirth, Ryouko became a new mother, yet struggled with her relationship with her son. She could not be intimate with her husband in front of their pubescent son, and the rare moments they did have sex left her unsatisfied. Her husband's libido had declined with age, and his selfish actions no longer made her feel loved. Overcome with loneliness, Ryouko began to pleasure herself. One day, feeling restless as usual, she jokingly provoked her son. That single choice would become the turning point that drastically changed her life.