Recently I have been hooked to martial arts novel. After reading some mangas, these are my current requirements. The manga should have the tag of school life along with it. I don't know why but so far the mangas that have school life along with martial arts have turned out to be good. Second requirement, should be more than 70 chapters at least. Third requirement, no harem or romance. No opinion on whether it has male mc or female mc. but it should have martial arts/action in it. Edit: Third requirement, should not be chinese. They have a lot of I will kill you/ You are no big deal (even though MC is complete beginner)
Mangas: The Breaker(72 chs) and The Breaker New Waves (200 chs) ("completed") Change Guy (338 chs completed ) History's strongest disciple kenichi (583 chs completed) Webtoons: Chronicle of the Heavenly Demon (not school, but it is my current favorite) (ongoing 141 chs) Volcanic Age (same, not school, but i do enjoy it) (ongoing 167 chs)
Among webtoons, you shouldn't forget "Gosu" (though it got a tad bit of romance, as does HSD Kenichi)
World's Best Martial Artist (439 chapters, dude returns to his high school days and plans to get rich! Reality shits on that plan immediately because he didn't return in time. The world is different in that martial arts are a mass spread and developed field without which you can't go beyond a city as a businessman or low level bureaucrat as govt employee. And he has nothing at first but still wants to see if he can hard work his way up that path for tue sake of being rich. He does discover a system, but there's no help at all and it's life risking to discover its functions). Martial Arts Master - very similar idea, 121 chaps available on webnovel/qidian, with differences caused by the fact this one was written by Cuttlefish( Embers Ad Infinitum,Throne of Magical Arcana, Lord of Mysteries, Sage Who Transcended Samsara) . The entire premise seems to have originated from someone who made it work very well and on this side of the language barrier, there is no telling which work that is or if it is even tled at all.
Maybe: Kenji Change 123 HSD Kenichi Baki Special Martial Arts Extreme Hell Private High School Sakigake!! Otokojuku Kongou Banchou GoHS Tenjou Tenge (not sure if there's a manga or not, only following the anime) Karate Shoukoushi Kohinata Minoru (university though, not HS)
History's Strongest Disciple is the best martial arts manga of all time its got a great plot plus the characters are interesting.
I haven't read manga for a while, but when I did, Peerless Dad was one of my favourites. It's a Korean wuxia about a single dad of triplets (don't worry, it's not slice of life) who joins a martial arts sect to pay for the cost of raising them. He doesn't realise he's one of the strongest members of the sect (gave up martial arts a long time ago for his wife, I think) and wants the boring and safe job of guard duty and things like that, while the higher-ups want him to use his extreme competency to complete difficult missions. There's a bit of school life later on when his kids are old enough to join the sect. I just checked, and it's currently at 242 chapters.