W Shokku ~Shin Gakuen Youshokutan~

A monster was sealed off by a monster buster long time ago. However, the monster still waits for his chance to get back. He tries to capture the monster buster's descendants, twin sisters, but he is defeated by the monster buster again. He somehow runs away and comes up with an idea that he disguises himself as a teacher and approaches them....

[From Erogeshop]