Wataru has recently begun noticing changes in his mother's body, and sneaking peeks at Ryouko while she bathes has become a habit. Ryouko is aware of his actions but says nothing, pretending to ignore him. One day, as Wataru sneaks a look as usual, Ryouko suddenly calls out, "Come in, I'll wash your body for you." Surprised at first, Wataru obeys and enters the bathroom. Seeing her son's hesitant form, Ryouko gently guides his penis into her vagina and accepts him. Amid a warm, tender atmosphere, a special relationship unfolds between mother and son.