I need help i cant find it!

Hey i'm searching for a title all i remember is that the little sister has a thing for her brother gets teased by her fellow friends in some sort of school sport club and then one day after practice she gets called to her trainer he then drugs her and rapes her over and over until she sucumbs to him and then she becomes part of this teachers harem and underground schoolgirl Prostitution ring or smth like that pls help i cant find it.