Due to an unexpected turn of events, a man ends up living with his wife's younger sister, Yukino. Unable to resist her allure, he approaches her while she is bathing. The timid and unable-to-refuse younger sister is forced into close contact in the narrow bathroom by the man. Having tasted the forbidden fruit, the man begins to grope Yukino even more stealthily, hiding from his wife's eyes. Eventually, Yukino herself awakens to pleasure and starts seeking out the man...
