Rio and I are not actually siblings. My father remarried and Rio was his stepdaughter... After our parents died, we lived together as brother and sister. Rio, who was so small at the time, has now grown into such a beautiful woman. I loved my step-sister... I confessed this forbidden love to only my best friend, Kenichi. But that was a mistake. Kenichi, knowing my feelings, forced himself on Rio and showed me lewd sex in our house that was so intense it made me go crazy...