Sankaku Opera

Sadaki Kaoru, an earnest literature professor who comes from a prestigious academy, hides in his heart the one-sided feelings he has for someone. One day, thanks to drawing the attention of the school troublemaker 'Shou, the informant' his secret is revealed. In exchange for Shou's silence, he'll have no choice but to have sex 'till the point of exhaustion.

(Source: Akaneshinsha, translated)