Four years into her remarriage, Yukari Emoto struggles with her relationship with Kousuke, her husband's son from a previous marriage. Unsettling incidents begin to pile up—Kousuke displays behavior suggesting he sees her as a woman, and she discovers her underwear missing after showers. One day, she sneaks into Kousuke's room and catches him masturbating with her stolen lingerie. When she confronts him, he suddenly overpowers her, thrusting their already tense dynamic into dangerous, uncharted territory.