Arima-san wa Omega ni Naritai

Arima Nijou is an Alpha who works at a first-class company who is only able to love other Alphas. At night, he pretends to be an omega and works as a call boy for Alphas. He wants to be an omega at least for a moment. One day, when he has no outlet for his sexual desire after a client suddenly cancels, he meets Mitsuki Izumi, an Alpha whose just his type. Izumi, a famous student entrepreneur, was arrogant, but his words struck a chord, and he was good at sex. It was a one night stand, but he was the ideal Alpha Arima was always searching for. Three years later, Arima goes to see Izumi with their child that he gave birth to?! Arima, who had an abnormal condition, presses Izumi to take responsibility, but it's not so straightforward.

(Source: Houbunsha, translated)