Mugongseogoui Juin

As an inept martial artist and a bastard son of the great Ha Clan, Ha Sochan had no choice but to become a vagabond. But his wretched life takes a turn when a mission brings him to the Martial Arts Library, a place filled with the secret techniques of the martial world. There, Sochan is accidentally bound to the library and sent back to when he was 12 years old. Now armed with the library's martial knowledge, he vows to make a name for himself in not only his clan but also the world!

(Source: Tapas)