For starter, it's not an anime about mahjong, it's an anime jerking off on criminals aka yakuzas. The main character has nothing to do with yakuzas but they are obsessed with him because of his supernatural luck. He is invincible and is treated literally as a lucky charm they try to own to help them with their infighting. And somehow, they are convinced that the games they lose trigger events in the yakuza world. It's weirdly religious, with its own logic, as you would expect an underground player to represent yakuzas and make them win something like territory or succession instead, not play with him like you pray Buddha. But I repeat, it's not about mahjong, the games are all the same, there is no suspense at all on that side.
It's all style no substance. The human lucky charm is the coolest man on Earth coldbloodedly playing mahjong and throwing few punchlines but that's pretty much all as he has ZERO personality. The criminals are sweating testosterone and are much more interesting to follow than the main character. Nothing happens much during every episode despite being 40+ minutes long. They frankly should have ditched the mahjong and focus on the power struggles.
But, somehow, it does ooze style even if vastly exaggerated and if you are watching that now, the 80-90s nostalgia will choke you and bring manly tears to your eyes.
Watch it for the style and expect it to be a little boring beyond that.