guys sister is getting married, and therefore they are having dinner together. guy ends up becoming friends with her fiance and they hang out pretty often. he feels safe with this gentle guy. turns out hes a scammer and used both him and his sister. even tho hes exposed, hes got the money. now his personality is tough, completely different. guy chases after him regardless. bumpy road, but ends up together.
Hitsuji no Kawa wo Kita Kemono