Hachimori Sumika loves her big brother! Because she loves him so much, she got jealous watching her childhood friend Aya getting a little too friendly with him. Going to a café by herself, her acquaintance Suzaki Yuri calls out to her and they end up going to a club together. At first, she was told that she can just talk to the guys there, but after talking about her brother she was told to have sex with the guys there as practice. Betrayed by Yuri, she was left alone in that place where everyone else was having sex. Why is this happening to me she think to herself as she goes home, only to hear the sounds of her brother and Aya having sex. Tormented, she heads to that club to find a place where she can forget everything