As a college student living with my older brother, I have a severe obsession with older sisters, and I spend my days living with a sexual fetish that can only be aroused by things related to older sisters. One day, Honami, who is about to get married to my older brother, moves in with us. Honami is more beautiful and has an incredible body than I imagined, and I'm feeling a bit embarrassed, but she smiles and says, "It's like I have a little brother! Think of me as your older sister!"... Wait, older sister? So, marrying my older brother means she's my older sister! I can't contain my excitement at finally having the "older sister" of my dreams. However, I try to control myself by telling myself that she's my older brother's girlfriend, but after the bath, Honami starts stretching, defenselessly showing off her big ass, and even asks me to help her. There's no way I can resist my older sister's sexy, huge ass in front of me...