Real Man - Chapter 3:

Once upon a time, there was a makeup artist who possessed outstanding skills and top-notch aesthetic judgement. When he did makeup for various stars, he could embellish sharpness onto the smooth vases that lacked edges, and he could make models who exceeded the boundaries of aesthetics to appear delicate and soft, more approachable to people.

Male stars loved to request him, for he had a thorough understanding of masculine charm in particular, and the makeup he did was never garishly slathered in oils or powders, instead exuding a natural, dashing air of elegance.

Female stars loved to request him, because not only was he excellent in his skills, he was also everyone’s closest confidant; when they chatted, he could easily hold any conversation, and his mouth would be tightly sealed, never allowing anyone’s privacy to slip out.

Although this person was quite young, after getting by in the makeup industry the past few years, he was virtually considered as a distinguished personality in his profession, and would be referred to as a ‘master’ wherever he went.

But he had a terrifying secret. He needed to carefully tread on thin ice and couldn’t expose even the slightest traces; otherwise, nobody would invite him to work ever again, and nobody would apply to the classes he led anymore.

—He was a straight man.

- Description from Novelupdates

Our protagonist Caam is a man from Earth that was reincarnated into this world as a demon. In order to survive, he spared no effort in avoiding the sparks of battle and without noticing it, he became strong himself.