Based on the erotic game by Mink. 
 
Alternative Story: A former science teacher receives a mysterious recruitment document, inviting him to a prestigious school. However, this school is not what it seems... 
 
Details Story: Teacher Ryuudouji Shimon is known as a teacher who trains people into sex slaves. On the orders of his old friend Sayaka, Mr. Ryuudouji was asked to conquer many women in school into his sex slaves. For the sake of pleasure and harem of torture, Ryuudouji is very happy to do so, especially Sayaka promises rewards to him. 
 
(Source: Nekopoi and Has Been Translated)