[Ribons Nights (Kyouno Aki)] Riajuu Kuroneko, Houkago ni (Ore no Imouto ga Konna ni Kawaii Wake ga Nai) [Digital]

I've read the manga last 2017 about a guy seeking for revenge for the men who raped his sister who committed suicide because of them. His sister apparently agrees to be sexually molested in exchange for money. And later on committed suicide because she thinks that she did a really bad thing. His brother met a girl that resembles his little sister but ends up being this girl's sex slave while she helps him find his sister's rapists. I really want to continue reading it but I can't seem to find it. Please help me out. Thank you!!!