Jisshuusei ~Kiken na Kyoushitsu~

Ryoichi attends a uni-sex (all male) school. Every year, his school hires student teachers. This year, two student teachers arrive for a 3-week training period. A stylish girl named Misaki Todo will be the P.E. teacher, and the big-breasted Nao Kurata will be the classic literature teacher. Kato, the school gang leader, decides to prey on these two young and sexy teachers. However, Kato 's teacher, Kanako Saiki, really gets on his case for trying such things.

Eventually, Kato gets his hands on Misaki. Soon after, Numada, a teacher with no morals, rapes Nao. She ends up becoming his slave. Kanako notices something different about Nao, and so she confronts Numada... Numada holds a secret over Kanako that she doesn't want revealed, thus resulting in her being forced into sexual acts.

Student teachers are neither students nor teachers. A new door opens up for these heroines.

[From Gamelex]