i believe it was omegaverse. it takes place in a prison. if you have any idea what it's called please let me know and thanks!
basically some dude makes a deal with some rich man to pretend to be a dead girl to appeal to the rich family's grandfather then he (cross dresser) meets the grandfather's grand child and they kinda bicker upon suspicion but eventually get along then they get engaged upon the grandfather's request then idk some time later the story progresses, the ......