Wit's manga / #enigma(1)

A real roller coaster that had many unexpected twists and turns. Starts with alpha third son of conglomerate is targeted by others. He is kinda tricked into having sex with a mysterious man and ends up being the bottom. Then he finds that he has been turned into an omega, but his father is on his death bed and there is a question of succession. Not to mention the man who turned him into an omega seems to have some past history with him...