Rio and I are not real siblings. Rio was the child of the partner whose father remarried. After that, she lost her parents and lived with her siblings. Rio, who was so small, has now grown into such a beauty. I loved my sister-in-law like that... She only confessed her forbidden love to her only best friend, Kenichi. But I was wrong. Knowing how I feel, Kenichi forcibly goes out with Rio and shows us nasty SEX at our house...