Yumi, a mother who lost her husband and raised her only daughter well, got married and came to live with her. One day, while they were living an ordinary but happy life, she happened to peek at her daughter and her husband's nighttime activities and was shocked. Her adopted son-in-law, who was a gentle and serious man, was making her daughter cum over and over again with his wild, intense hip thrusts. Seeing this brought back memories of her time as a sex addict and creampie slut, and she couldn't control her sexual desire...