One day during the holidays, Souta comes to stay at his friend Hiroshi's house and discovers a shocking truth. Hiroshi's mother, Yumi, spends all her time at home completely naked. Excited by his childish Kokoro, Souta hugs Yumi. Yumi tries to warn him off, but he is so excited by the big dick despite his small body that he ends up swallowing it all the time...