My parents remarried and I suddenly got a busty step-sister. My step-sister is Misato and has the same innocent personality as her mother, but she is always braless at home. I get a secret erection every time I see her boobs. "Big brother, are you a virgin? Have you never seen boobs before? Shall I touch them?" I got mad at her teasing me with her boobs, and my desires went out of control and I attacked her... From that day on, I took advantage of my parents' absence and had sex with Misato nonstop.