Another great manhwa that I've read numerous times over the year: Transfer Student Storm Bringer by Gangnengyi. As an aside, there is a Transfer Student Storm Bringer Reboot. It is not good. Compare the original's 92 chapters to the reboot's 19, and you get the idea.
The story follows Ju Ingong, a name that literally translates to Main Character. Ingong was born with a badass face. He has resting badass face essentially. So people thought he was a badass and fought him. Unfortunately, he's weak and a coward. When this was confirmed, he became a target of bullying. He learned to go with it, and bluffed as much as he could to get out of fights.
The story begins with Ingong transferring to a new school. This school is ruled by grade Jjangs, essentially strong fighters who represent the school. While schools normally only have one Jjang, this one has one per grade. The Jjangs are currently in a stalemate. After Ingong accidentally kicks his grade Jjang's ass, he becomes the new Jjang of the grade, and sets off a series of events that shakes the whole school.
Aside from all the fighting, there's a deep story found within. It takes a few chapters to find, but that's all world-building, and it's well worth it.
That's his power though, he accidentally kicks ass. He wrecks the scariest guys around, and it's a thrill to watch. That kick to the left? He tripped over a soda can, landed on his ass, and his leg hooked that guy's neck. He tried to get up, but tossed that guy into the wall. This all happened in a second or two. He didn't know what happened until after the fact. He tried to fix it by going to apologize, but ended up kneeing the guy right in the face.
(The moment was not prepared for.)
The characters really sell this manhwa. Ju Ingong is fun to follow. Wan-Suh, the guy who got wrecked, becomes Ingong's friend/lackey/guide to the school. The other Jjangs are these badass fighters who are all angling to be the school Jjang. One of them is a hot girl. She's crazy, but hot.
The art style looks a bit rough here and there, but it's great. The characters are varied, the fight scenes are something out of Dragonball Z, sans energy beams. The fights don't follow a predictable route, there's always a twist newer readers won't see coming.
All said, it's a quality high school martial arts series, one of the best around. It's definitely worth a look for fans of the genre. It deserves an anime or something. Definitely warrants it more than most other series of the genre.
