Usotsuki Watashitachi no Koi wa

I have been in love with my sister's fiance for 7 years. I live a lie. That has never changed and never will. Or so I thought... Until I met Eichi. The day Eichi found out about my lie, that I was okay with my sister being with her husband, he told me that he wanted my sister for himself. We decided to work together to make our fantasy a reality. But, the way Eichi was coming on to me made me question if it was really my sister he was after. To grow accustomed to a man's touch, he hugged me... and even k-kissed me?! What in the world is going on? (Source: Manga Plaza)