Machi Gurumi no Wana: Hakudaku ni Mamireta Shitai 4

Based on a game by Syrup.

On the recommendation of her father's friend, Takagi Atsuko takes up a teaching position at Nansui Academy. One day, pictures taken by a peeping tom are put up on the notice board. The identity of the culprit is unknown, but suspicion falls on the class outcast, Murayama Kenji. Atsuko defends Kenji, whose father is the Academy's principal, publicly. However, the truth is that Kenji is using that authority to force Atsuko into many sexual and perverse acts. Some of these in public. Soon, Atsuko finds her body craving for even more...

Later, Takagi Yui, Atsuko's younger sister and a student at Nansui Academy, discovers what is happening. In order to help her sister, Yui approaches the Murayamas...