During a holiday night, Sota stays over at his friend Hiroshi's house and is shocked by an unexpected turn of events. Hiroshi's mother, Yumi, always walks around the house completely naked. Sota, stirred by childish curiosity, feels an uncontrollable excitement and instinctively moves closer. Though Yumi tries to stop him, his small body trembles with intense arousal, and he finally embraces her. In that moment, her heart begins to waver...