No.1 Omega-sama wa Unmei wo Shinjinai

Overview

An alpha terrified of other alphas meets a proud omega. Their undestined love begins with a fake relationship contract. Aka, the top-ranked omega at his club, one day gets requested by Soei, a rich heir way out of his element. Aka's more than excited to land a wealthy client, but it all goes downhill when Soei's sympathetic look enrages him instead. In this world, alphas are said to be superior, but Aka is certain that it's the other way around... omegas are the ones who really rule the world! The two spend a night together, surrendering to their instincts and losing their senses. Soei takes a liking to Aka and, to the latter's dismay, then introduces him to his parents as his fated pair. It turns out, Soei just wants to get out of an unwanted arranged marriage. He pleads and presents Aka with a lucrative fake partnership contract. Does this mean Aka will finally have to face the one thing he's evaded his whole life ― fate!? (Source: Renta!) Note: Includes an extra chapter.

Source: AniList