Deatte Hitotsuki de Zecchou Jorei!

Climax Exorcism. It is the obscene ability that forces anyone, dead or alive, to climax when penetrated. And as a side effect, it also causes evil spirits and monsters to become purified and exorcised when they cum. Haruhisa Furuya, the boy who possesses this unholy ability, is one of the lowest-ranking students at the Exorcist Academy. After all, if he uses his ability, it would destroy his social standing (among other things)... But then Haruhisa meets someone, a girl named Misaki Souya, a girl with an evil eye capable of exposing people's secrets.

(Source: Gagaga Bunko, translated)