Mari, a friend of the mother's, comes to Tokyo accompanying her husband on a business trip. Her son Kazuya is thrilled to hear she'll be staying over. Meanwhile, Mari has always felt a lingering awkwardness toward Kazuya ever since she once caught him masturbating. But now, seeing him grown into a strong young man, her heart begins to stir. Using intoxication as an excuse, she impulsively kisses him. Mari's body, long deprived of a man's touch, ignites with passion, overriding reason as emotions take control... Their relationship slowly evolves into something deeper than friendship.