Shikaeshi Game ~Shasei Sasenai to Shinu Death Game~

The protagonist has trouble with communication, and at the bottom of the school caste, he is easy pickings for the three female bullies in his class. One day, he notices a weird app installed on his smartphone "Revenge Game" and out of curiosity, he inputs the names of the three girls who are bullying him.

He immediately loses consciousness, and then awakes to find himself at school, at night, with no-one around... but the three bully girls right before him. At first both the protagonist and the girls are confused and panic that they have been trapped at school, but then the rules of the "Revenge Game" are announced and...

It would seem that they they are now participating in a Death Game, where the girls have to keep making him cum... or DIE. Thus begins our protagonist's tale of sweet sweet erotic revenge...

[From DLsite English]