One of the first manga I actually reread more than twice. It is easily my favourite martial art manga, and one of my favourite manga overall. The characters are all memorable, even those that lose early on, all specially designed with a wide range of martial arts, backstories, motivations, etc, and you may hate some, but if you hate them they must be memorable.
The story is rather simple on the surface, and that, in this scenario is a very good thing, because it lets you focus on what truly is the star of the show, the exhilarating fights. The fights are the best I've seen in manga, period. They are very technical, using martial art techniques true to the real world, and fantasy techniques that take a blend of real ideas, as well as a fantastic twist. 11/10 fights, every single one of them.
The art develops as the series develops, and it gets better and better, never declining over the many chapters of the manga, which is especially hard to keep up with the heavily technical nature of the fights involving BJJ/Grappling, which is a certain 10/10.
Overall, if this manga is very underrated/overlooked by many in the community, but it is an incredible journey with an average businessman, and a man in the Kengan matches called the Ashura.
10/10, Peak fiction, the absolute pinnacle of martial art manga.