Shinai naru Omega e
親愛なるオメガへ · しんあい なる おめが え
est. Rough estimate based on volume count, reprints and magazine — not an official figure
Overview
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)
Source: AniList
External databases: MADB · AniList
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