I have two childhood friends who are sisters. The older one is my age, and the younger, Mirei, is three years younger. We used to play together as kids, but as we grew up, I rarely saw Mirei. One day, the older sister confessed her feelings, and we started dating. I visited Mirei to share the news, but she didn’t seem happy—perhaps feeling like I’d stolen her sister.

When I was invited to Mirei’s house again, I was shocked to see her dressed provocatively. 'Mirei, why are you dressed like that?' I asked. 'What? Isn’t it cute? This is my house,' she replied, flaunting her figure confidently. Mirei pressed her chest against me, making it hard to meet her gaze.

It turned out Mirei had feelings for me all along! That’s why she was upset about my relationship with her sister. Despite my girlfriend being nearby, Mirei tried to seduce me, showing off her full breasts. I never noticed how curvaceous she was. When no one was looking, she even gave me a quick thrill.

At first, I went along out of curiosity, but Mirei’s temptation grew stronger. While my girlfriend was drunk, Mirei straddled me, and we secretly hooked up. I knew it was wrong, but the thrill was intoxicating. Though I was betraying my girlfriend, the satisfaction with Mirei was hard to resist.

Thus, I was drawn into a secret affair with my girlfriend’s sister, where irresistible passion kept unfolding...