Shinai Naru Omega e

Mio Karino, who works as a secretary, hides the fact that he is an omega under the young master, Nagao Keisei, who dislikes omegas. Although he was embarrassed by Keisei, who does not believe in people, Keisei also devotes his heart to Karino. However, he was told that Karino was an omega, and he ordered him to leave. There is a circumstance where he cannot return, and he uses drugs to forcefully return to Keisei!
(Source: Kadokawa, translated)