I'm looking for a protagonist who hides their real emotions behind a facade, it doesn't matter what their real emotions or facade are, they just gotta hav'em. Good examples include : My Death Flags Show No Sign of Ending, Youjo Senki, (Dungeon Defense, I guess ?, just included it so people don't recommend it below). Bonus points if their facade is a character they're playing, like in Youjo Senki, she's playing the typical loyalist soldier(that also happens to be a genius when it comes to war tactics).
maybe Akugyaku no Black Maria, Maou Gun Saikyou no Majutsushi wa Ningen datta, maybe Isekai Maou to Shoukan Shoujo Dorei Majutsu? do dual personailties also count?
A Will Eternal. He often tries to act like a "lonely hero" instead of a cowardly, funny guy. Otherworldly Evil Monarch. For a while, he acts like the rich young master he transmigrates into.
+1 good novel it's my favorite one also it's a great comedy i really recommend you to read it @Parpaing
If multiple personality counts then I recommend my story the Vespidian. It is a superhero story about a girl who gets turned into a wasp monster who has urges and has conversations with herself, or rather Sub the entity living inside of her head. It is a bit on the pervy and dark story. Might be what you are looking for, ps not till arc 2 that Sub is introduced.