Incest: My beloved son is taken away...

Three years after losing her husband, her mother, Eriko, has become accustomed to living alone with her only son, Koichi. One day, when the days of peaceful life continued, an incredible sight leapt into Eriko's eyes. Housewives' friends Fumie and Koichi are hugging each other half naked! It feels like my beloved son has been taken away by someone else...and he is an old friend whom he trusts. Her sadness and anger, which seemed to be betrayed, drive Eriko to unexpected actions...