Gakuen no Shuryousha ~Noroshi~

Revenge never felt so good!

After Noelle's parents die suddenly in an accident, her older stepbrother Shuuichi returns to take care of her - in ways she could never have imagined. Noelle is horrified when, on the very night of her parents' funeral, the stepbrother she remembered so fondly cruelly rapes her. Then, without explaining why, Shuuichi forces Noelle to transfer to the prestigious Takamine College.

Each night as he ravishes her body, Shuuichi pumps Noelle for information about the women on campus. Women like the curvaceously timid Haruko, the sexually talented Shirone, and the beautiful blond-haired bombshell Elena... Women who will be able to satisfy his insatiable desires - and provide him with the information he needs to avenge the death of his mother.

[from AniDB]