Three years had passed since our marriage, and my wife became pregnant. She wanted to give birth at her parents' home, so she decided to return there. I thought that maybe it would be nice to have some alone time again, but my wife's younger sister came to help with the housework. The little sister-in-law I hadn't seen in a while had grown up completely and had a great figure, very attractive; though I knew I shouldn't think this way, I couldn't help but look at her as a woman. Thinking about being alone with her in the same house made me uneasy. Then, I saw my sister-in-law masturbating and couldn't hold back any longer...
