One Punch-Man, Mashle Recommendations
Simple-minded protagonist gets themselves into power struggle and hierarchy of those who weild unnatural powers. He proceeds to beat through problems he encounters with pure raw strenght and carefree attitude.
Both have a main character that are comically overpowered, and both also have similar comedy. While mashle isn't as good as OPM, you'll probably get some enjoyment at least from it at least.
Both the main characters have insane physical strengths, so much so that both of them defy the logics of their world. Also the facial design of both the protagonists is quite same, Mash looks like a Saitama with hair, and both of their sense of humor is quite similar too.
Mashle and one punch man are quite similar in their way of comedy.
The setting of the 2 stories however is a little different. Mashle is set in a magic world, where OPM is set in a "regular world".
Both have the same kind of main character. Overpowered with just brute force strength alone, both are just ordinary people surrounded by people with real convictions and abilities. Instead of heros (like One punch-man) Mashle has a world with magic and a lot like Harry Potter!
Both protagonists have physical strength well above human limits. They also both have really aloof personalities where they dont seem to care about many things. The gag comedy style of both mangas are also insanely similar.
Both stories contain a overpowered protagonist with top point comedy. Mashle has some good fights,(not on the level as one punch man) and the story is simple enough.