Still living with her parents, freeter Tomonori spends his days without ambition. One day, Eriko, a friend of his mother and a married woman struggling in her marriage, comes to visit. Tomonori has long harbored a childhood crush on her, and his heart races at their reunion. Eriko, however, gently rejects his feelings, dismissing them as mere infatuation. Yet moved by his sincere devotion, she agrees to one night together under the condition it never happens again. Afterward, Eriko softly murmurs, "I see... youth really is something," and their relationship gradually deepens. Naturally, emotions grow between them, forging a new, intimate bond.