Shortly after getting married, her husband is transferred for work and must live apart from her for three months. Worried about her living alone, she moves in with her older sister and brother-in-law. Life continues peacefully, but her sexual frustration grows day by day, leading her to seek relief through masturbation almost daily. One day, she discovers that her brother-in-law, Tetsuya, is also suffering from a sexless marriage, and feelings for him begin to stir within her. Tetsuya is well-endowed with a large cock, yet even that fails to satisfy her escalating physical cravings. Unable to suppress her desires any longer, she secretly seduces him, and he, unable to resist her mischievous charm, gives in and begins a forbidden relationship. This affair becomes the means to fulfill both her emotional and physical longing.