Ayumi, a daily-life girl with a brother complex, can't resist her growing attraction to M-kun. She catches him masturbating in the bathroom, his thick cock hard and ready. Embarrassed but intrigued, she joins him, their incestuous desire building as they stroke each other's bodies. He pushes her against the wall, his fingers teasing her wet pussy. She moans, her brother's touch igniting a fire within her. But their forbidden love is interrupted by a knock at the door, their secret at risk of being exposed.