The main characters of this manga are politicians and other historical figures of various countries and periods of time that engage in sometimes absurd activities and, most importantly, mahjong fights, that consist of fighting the evil side through various mahjong shenanigans. At times the story gets so cringy that you laugh from the sheer cringe of it.
Important to note that if you don't know much about mahjong and its rules, then your experience might be more boring than it could've been. Also the events unfold so fast and so often that you lose track of them and don't really understand what's going on, this manga doesn't really have a storyline.
Yet still, this manga is drawn well, it has lots of quite funny political and historical references, though not all of them are historically accurate but that's done just for the laugh (some of them are straight up absurd, which is why they're often the best). Also be ready for some nudity and lots of swastikas.
To put it shortly, Mudazumonaki is a nice manga for some chill. Wouldn't call it exceptionally good or funny though, but it has some really funny moments. Yet if you're not into mahjong or not interested in history then you might find it boring