I'm a college student living with my brother, and I'm a super-sister-loving guy. I can only get excited about things related to my sister. One day, my brother and I'm married to Honami, who is about to get married. I'm flustered by Honami, who is more beautiful and has a great figure than I'd imagined, and she smiles and says, "I think I have a little brother! Think of me as your big sister!"... What? Big sister? I see, if I marry my brother, she's my big sister! I can't contain my excitement at having the "big sister" I've always dreamed of. However, I try to control myself by thinking that she's my brother's girlfriend, but after the bath, Honami starts stretching while showing off her big ass, and even asks me to help her. There's no way I can resist my sister's sexy big ass in front of me...