 If you liked
Koisuru Boukun
|
 ...then you might like
Kyuuso wa Cheese no Yume wo Miru
|
Similar plotlines. A gay man feels a long-term, unrequited love towards a straight man. He then manages to blackmail the straight man into having sex with him. Romantic feelings ensue.
Similar plot the main character is in love with his straight sempai for years and uses a blackmail to finally get sex with him, and by passing the time the sempai will be accepting his feelings.
But they have a different essence because one is more realistic, Koisuru Boukun has more comedy and has a lighter story, of course the romance is in both mangas.