One night and two days of 1 night and left alone by my wife's sister who suddenly came over

While his wife was pregnant and went back to her parents' house, Kazuya struggled with unfamiliar housework for his wife and child. However, his struggles continue to vanish and his house continues to clutter. At that moment, my wife's sister, Yuri, came over to help with housework. Kazuya is confused by the sudden visit but is happy, but Yuri's true purpose is to relieve her frustration that has accumulated over time with her younger sister's husband... Without realizing that, Kazuya is completely relieved to be able to clean and cook homemade dishes, and goes to a bath without a defense. Yuri, with a mysterious smile on her face, said to let her back flow, and she was about to come in...