Two days have passed since Kenichi saw his wife off on a trip. The living room was already in such a mess that it was impossible to fix. But his wife's older sister, Kaho, appeared as a savior. Kenichi was surprised by her sudden visit, but he was eternally grateful to her for helping him with the housework. To repay her kindness, he promised to let her stay the night, but that night, while Kenichi was relaxing in the bathtub, a naked Kaho attacked him. "What are you doing, sister-in-law?" "I was just going to wash your back." The softness of her big breasts pressed against his back made his penis rise involuntarily...