Every night, the sounds of intimacy drift through the wall... Shinkai, a middle-aged man living alone, finds his quiet life disrupted when the Nishikawa couple move in next door. The old house has thin walls, making it impossible not to hear their conversations and moans. Shinkai becomes increasingly drawn to the voice of his neighbor's wife, Yui, and his desire soon spirals out of control. One day, after secretly checking a delivery addressed to the Nishikawas, Shinkai lures Yui to his place under false pretenses, initiating a forbidden relationship. He begins ambushing her on her way back from throwing out the garbage, teasing and provoking her repeatedly. Gradually, Yui's body starts craving the pleasure he awakens in her...