Shiori lost her father to illness and began living with her mother's new husband and his son, Kiyoshi, becoming step-siblings. Kiyoshi, depressed after failing his college entrance exams, gradually starts developing feelings for Shiori. Though they are step-siblings, their emotional boundaries begin to blur. Kiyoshi, overwhelmed by stress, becomes increasingly fixated on Shiori's body, while she responds with cold indifference. One day, Shiori discovers that Kiyoshi has been secretly filming her, filling her with contempt. Overcome with arousal, Kiyoshi reaches out to her—but what awaits them both is beyond either of their expectations.