[/SPOILER
Red Storm (I can't recommend this enough. A lot of its action involves military tactics and armies, great art, and a mentor character that could beat Gojo's ass. The political and cultural aspects of the story are strong too.)
Reincarnated as an Unruly Heir (there's a bunch of murim manhwa where a good guy ends up in the body of a dark martial arts sect, and I like this one best of the bunch)
Fists only:
Worst and Crows are GOAT'ed in my book (It's arguably the most recognized delinquent manga in recent history for a reason)
Teppu (this is an MMA manga where the combat is realistic. You could use some of the artwork to teach proper form on certain strikes and submissions. It's also, just plain good).
Kengan Ashura/Omega (Kengan Ashura is a straight up tournament manga. Kengan Omega starts similarly but expands the world a lot)
Clover (This is a delinquent manga that I don't see mentioned enough)
Viral Hit (kinda like someone took the Holyland premise and turned it into a comedy with influencer-culture replacing the "streets" lol)
Out (kinda goes off the rails later on, but I love the first bunch of arcs. But I like that it goes beyond just honorable HS fights. The cats are dealing with gangsters, catching bodies, and dealing with real gravity to their actions)
