Kobayashi and her son come to celebrate the Kirishima family's new home. However, Junpei, the son, is more fascinated by the huge breasts of Sakurano, the mother of the Kirishima family, than by the house itself. Junpei can no longer suppress his sexual desires as he touches Sakurano body and bathes with her, and eventually sneaks into Sakurano bed and forces a physical relationship. Then, Sakura gradually begins to expose Kokoro and body to Junpei...