Gosu

When his master dies, Gang Yong pledges to avenge his teacher at all costs. After training his martial arts skills in seclusion, Gang Yong sets off to hunt down the traitors and make them pay! But when he gets to town, he discovers they're... already dead? Well, what's he supposed to do now?!

Original Webtoon:
Naver Webtoon, Naver Series
Official Translations:
English, Japanese, S.Chinese, T.Chinese