Responses
I GOTCHU!!!! I read this yeaarrss ago and there hasn't been many updates ever since I'm sooo sad but it's an interesting plot and the art is nice so I go back to it every now and then!
https://www.mangago.me/read-manga/hitsuji_no_kawa_wo_kita_kemono/

okay so it’s a manga and i think the uke in the story falls for his sister fiancé? And the fiancé is a scammer. He’s not really in love with her sister. He’s just deceiving her for whatever reason so yeah that’s the story from what I remember I could be wrong.