After her husband's passing, Nanami raised her only daughter alone. Her daughter, now grown and married, lived with her, enjoying a simple yet happy life. One day, Nanami accidentally witnessed her daughter's nighttime activities with her husband and was shocked. Her son-in-law, usually gentle and earnest, was passionately and intensely making love to her daughter. Seeing this, memories of her own past as a sex-addicted, in-and-out playgirl resurfaced, and her sexual desires became uncontrollable.
