Kazuki, a college student, spends his Sunday cooped up alone in his room with no girlfriend to keep him company. Seeing her son's reclusive behavior, his mother voices concern to her husband, but he dismisses her worries with a joking remark: "Maybe Kazuki's got a thing for you?" The comment sends a sudden jolt through her. Later, as she gathers laundry to wash, she finds Kazuki's underwear among the dirty clothes. Holding the fabric in her hands, overwhelming emotions surge within her, impossible to suppress.