Aoyama Aina and her husband move into a new apartment after getting married. Aina, a beautiful, gentle, and modest married woman, soon catches the attention of their neighbor, Sakaguchi. While her husband is away during weekday afternoons, she begins to transform into someone entirely different—giving in to raw, hidden desires. A secret love affair unfolds within the quiet walls of the apartment complex, as Aina becomes the neighbor's creampie sex slave.