Based on the game by Kiss.

Arisugawa Academy. An all-girl school well known for its high standards with the upper class. However, there is a dark side to this educational facility. The Chairman of the academy, Takahashi Hiroaki, is actually a member of a secret organization whose prime objective is to cater to the sexual desires of government officials. Mutsuki Sayoko has fallen into the hands of this sinister being, who leads her to the path of libido. A high-class, well-behaved student or a horny, wicked sex slave... which is the true her?

(Source: AniDB)