Five years after separating from her husband, Setsuko has been having an affair with Masao, her son Satoshi's friend. As their relationship intensifies, Setsuko grows jealous and decides to provoke Satoshi by secretly recording her erotic encounters with Masao. She deliberately leaves the video in Satoshi's room, hoping to incite his anger and jealousy. That night, Satoshi barges into his mother's room, overcome by an uncontrollable urge to have her for himself.