Shihori is married to an older man who is the father of her only son, and though they live together, their intimate life has become dull due to his age, leaving her to endure daily frustration as her body aches for release. Lately, she's begun to notice the gaze of her stepson Kouta, with whom she rarely speaks. Unbeknownst to her, Kouta has secretly been stealing her underwear for some time. One day, overwhelmed by his pent-up desire for his stepmother, he blurts out, "I can't take it anymore—just the underwear isn't enough!" His confession sends an unprecedented tremor through Shihori's heart.