The Breaker

The new English teacher, Chun-Woo, is not your ordinary teacher. Shioon, a victim of constant bullying, unexpectedly witnesses Chun-Woo's fighting prowess, and begs him to make him his disciple. Chun-Woo claims he can teach Shioon only if he is truly determined, and Shioon must put his life on the line to prove it. It turns out, however, that Chun-Woo and his powers are more than meets the eye. Shioon makes a grand entrance into the Murim (the hidden world of martial arts), and he is about to be taught by the best there is!

The Breaker series has 2 parts, of which "The Breaker" is Part 1 (vol 1-10) and "The Breaker: New Waves" is Part 2 (on-going).