On the verge of marriage, Atsushi and his fiancée Kana spend their days together at her home, making wedding preparations. Yet Atsushi's thoughts are never of Kana, but always drawn to her mother, Yui. Having raised her daughter alone after a divorce, Yui's strength and tenderness captivate Atsushi completely. One day, learning that Yui was bathing, Atsushi sneaks into her room. There, he finds her freshly discarded underwear and unconsciously brings it to his nose, inhaling her scent. At that very moment, Yui steps out of the bath. The sudden tension and mutual attraction between them sparks a forbidden story.