Karate Shoukoushi Kohinata Minoru - Baba Yasushi
This is an awesome manga. If you long to read a battle manga that is more rooted in reality then this one is for you. The action isn't too over the top and the fighting principles are all based on the real thing. It isn't really a very serious seinen manga like others in this thread. You'll laugh a lot reading through this. It's a seinen manga with a shounen main character. Well, I can say that it's just borderline seinen. This can actually be shounen if not for few nudity and a little gore. I'm sure there'll be some debate on whether which martial art is the deadliest. I hope you'll enjoy reading this manga.
Kohinata Minoru is a college student at a college that is popular for its sports rather than academic orientation. He starts out as a gymnast alongside his friend, Nana, but is bullied by his gymnast seniors. One evening, a karate student at the college, Mutou Ryuuji, witnesses Minoru being bullied and comes to his rescue and drags him into the world of karate. Minoru makes new friends and learns some of their dark pasts, including a shocking death that reveals motives for revenge.