Mirei is Mika’s younger sister; we three grew up together. As we got older, I rarely saw Mirei but often met Mika since we were classmates. Later, Mika and I started dating. Visiting my girlfriend’s house, I saw Mirei again. It hadn’t been that long, but each time I saw her, she seemed more alluring—especially her large, perfect breasts that caught my eye! Knowing I was drawn to them, Mirei wore revealing clothes to seduce me. She’d liked me for a while but grew jealous seeing me with Mika, so she decided to steal me. Even with her sister nearby, Mirei teased me by pressing her breasts against me, letting me feel their softness and bounce. Though I kept saying ‘no,’ my body betrayed me. Despite my guilt toward Mika, I couldn’t resist her irresistibly sexy sister!