Fangs and Honey

Defying their instincts, a coup in the omegaverse! This society is full of inequality when it comes to secondary genders.

Mao, a yakuza and Alpha, hates his own and has been pretending to be a Beta, which leads to him being assigned to look after Hiragi, the chairman's grandson and an Omega with an "unusual constitution." One day he stumbles upon Hiragi in heat. Unable to resist Hiragi's powerful pheromones, they end up having sex. But despite his innocent appearance, Hiragi is cunning, and when he realizes Mao is an Alpha, he forces Mao into helping his plans for a coup...!

(Source: MangaPlaza)