I never thought my father was raping my sister... Someday, I will become lustful for my sister. That's why I ran away from my sister.

Eight years ago, my father remarried and Riho and I became brother and sister. Although we are not related by blood, we have become family. To a happy family. But...I had become aware of my sister as a woman before I knew it. I was scared to be with you. I wonder if someday I'll end up lusting after my sister. So I ran away from my sister. I used my busy university life as an excuse to run away from my desires, and before I knew it, I hadn't returned home for a year. During that time, Riho was raped by her father...