After her husband broke their promise to have sex, Sora, a wife, indulges in masturbation to spite him. Her stepson Makoto, who had been watching her, sneaks into Sora's futon. As her husband sleeps beside her, Sora desperately resists, but she eventually gives in to the sweet whispers of Makoto, a young man with no blood relation to her. In this dangerous situation, Sora desperately tries to suppress her voice, while Makoto thrusts his penis deeply and deeply in and out, trying not to make any noise. From that day on, the forbidden adultery between the two escalates, and they begin to seek even more stimulation and pleasure...