Three years have passed since we got married, and my wife got pregnant. She said she was going to give birth at her parents' house and decided to go back home. I was thinking that living alone for the first time in a while might be Ari, but my wife's younger sister came to help with the housework. I met my sister-in-law for the first time in a while, and she seemed cute, had a nice figure, and was very attractive. Although I knew it was wrong, I couldn't help but see her as a woman. I couldn't calm down thinking about the two of us being alone in the same house. Then, I saw my sister-in-law masturbating, and I couldn't help but approach her. Since then...