This is actually two games, but the RPG is really the primary game. You play a short-haired brunette girl at a women's academy, battling against a variety of female opponents in an attempt to get to the bottom of the attacks on girls at the academy. Most of the hentai is at the end when you win, and is dependant on what items you collect during the game.
There is now an english translation of this game from Nana vs. Nana. You can download the patched version (1.10) below.Download English Version