Kobayashi mother and child who came to celebrate the new construction of the Kirishima family. However, his son Junpei is more fascinated by the huge breasts of Sakura, the mother of the Kirishima family, than at home. Junpei can no longer suppress his sexual desire while touching Sakura's body and taking a bath with him, and finally sneaks into Sakura's bed and presses for a physical relationship. And Sakura gradually exposes her mind and body in a smooth manner ...