Takahashi and Yamada, two of her husband's students, come to stay overnight for tutoring. That night, Mizuki, neglected by her husband, indulges in masturbation, unaware that Takahashi is secretly watching. The next day, Mizuki seduces Takahashi, and the two engage in passionate sex. Later, while her husband sleeps, she sneaks into the boys' futon, becoming deeply involved in secret affairs with both youths. As their intimate relationships grow, complex emotions begin to unfold between them.