Yumiko, after losing her husband, lived alone with her daughter. Later, her daughter got married, and the three began living together. One day, Yumiko returned home to find her daughter and son-in-law secretly intimate. Trying not to be noticed, she held back but couldn't help wetting herself at the entrance. Her kind son-in-law noticed and quietly cleaned it up for her. That night, the son-in-law complained that his wife rarely had sex with him. Yumiko, naturally responsive to affection, gladly accepted his advances, exchanging kisses and making love. From then on, the two continued to desire each other, deepening their forbidden relationship.