Based on the erotic game by Bishop. 
 
The protagonist Ryou Kawabata is someone who enjoys watching women his senior succumb to him. As a student, it is obvious that the targets closest to him are the female teachers. 
 
As numerous female teachers succumb victim to his will, unexpectedly there was one who fought back- Yuuna Hagiura, and that gave Ryou some trouble. But even as the Hakushou Academy was informed of Ryou's misdeeds by Yuuna, the whole incident was kept behind closed doors because of the risk of ruining of the school reputation if the incident goes public, and instead Ryou was forcibly expelled under the guise of a school transfer. Thanks to this, his crimes goes unpunished and he enrolled as a transfer student in Jyousei Academy in the neighboring town. 
 
Before the day of his transfer, he meets a teacher who shares the same looks as Yuuna during his visit to his new school. Her name is Aina Hagiura. As it turns out, Aina is the younger twin sister of Yuuna. Thanking the devil for his good fortune, Ryou goes on the hunt for this new prey. 
 
Moreover, there's also the school principal Mifuyu Kamijou, a woman enveloped in adult womanly charms, and her arrogant daughter, the head of the public morals committee, Marika Kamijou; and Hatsune Amagi, the student council president with a mature personality and zero complaints in both looks and grades. 
 
Along with these attractive candidates to be his prey, Ryou also discovers that a teacher of Jyousei Academy is his already 'trained' stepsister, Takatsu Narumi. With Narumi becoming his new partner in crime, so begins the hunt to satisfy his carnal desires in a new ground.

Sansha Mendan: Rensa Suru Chijoku Choukyou no Gakuen