This happened a year ago. With her husband no longer coming home even on holidays, Reiko's sexual desires were building up. One day, Reiko accidentally witnesses her only son, Yu, masturbating, and her pent-up sexual desire finally erupts. From then on, she and Yu have a forbidden affair every day. Reiko feels her own nipples becoming more and more sensitive due to Yu's abnormal obsession with nipples, a mother-boy. Even though she knows in her mind that this is an unacceptable act, her body, or rather her nipples, are addicted to Yu's caresses.