Rio and I are not real brothers. The partner's stepchild whose father remarried is Rio. After that, I lost my parents and lived with my siblings. Rio, who was so small, has now become so beautiful. I loved my sister-in-law like that… I only confessed such a forbidden love to my only close friend, Kenichi. But I was wrong. Knowing how I felt, Kenichi forced himself on a date with Rio and showed us obscene SEX at our home…

Taking his friend home, he accidentally discovered that he was fucking his beloved sister