Mary and Masaaki are step-parents. Masaaki desperately tried to suppress Mary's sexual desire for Mary, who was beautiful and close to her age, but who was full of motherhood. However, the more he suppressed her carnal desires, the more Masaaki's mind and body weakened. Masaaki couldn't stand it and decided to leave home, and finally he decided to go on a hot spring trip with his three parents. With this, Masaaki and Masaaki should have been able to cut off their feelings for Mary, but...
