有馬さんはオメガになりたい

Arima Nijo's an alpha working at a top-ranking company. Ever since he was in middle school, though, he's only been able to fall in love with other alphas. Now, he disguises himself as an omega and works as an escort at night. Even if only for a few moments, pretending to be an omega fulfills him... One day, after a client cancels on Arima at the last minute, he meets Koki Izumi, a man whose appearance is just his type. Izumi's a college student who's also a famous entrepreneur, and while he can be pretty arrogant, he's great in bed. Even though it was a one-night stand, Izumi was Arima's ideal alpha. Three years later, Arima reunites with Izumi and introduces him to... their son, Ayumu! Due to Arima's unique biology, he is able to give birth, and he wants Izumi to take responsibility... (Source: Renta!) Note: Includes two extra chapters.