Father left home after having an affair with another woman. Since then, mother Yuna forgot how to smile and always looked melancholy. Seeing her like this, Toshiya ached inside. From now on, he would support his mother. With pure intentions, he drew close to her, trying to warmly embrace and comfort her. But overwhelmed by loneliness, Yuna began craving her son's body. Deep down, she had feelings for him too. Toshiya accepted her emotions, resolving to step into the forbidden world together.