Yuko has had a physical relationship with her son while her husband is away on business. She can't continue this immoral relationship forever. On the day her husband's business trip ends, she tries to bring an end to their rotten relationship, but... "Is that really okay, Mom?" Having gotten a taste of her son, Yuko's Kokoro wavers. However, she cannot give in now. Shaking off her unwilling son, Yuko declares that they are ending their immoral relationship. This day heralded the beginning of their long and final sexual encounter...