Akyeokmussang

Heli Yun, notorious degenerate, shocks everyone by suddenly turning from his lowlife ways. No one realizes he's been possessed by Lee Siwoon, the author of Heli's story! Trapped in the martial arts novel he wrote, Heli knows that unless he gains power, he's headed for a villain's death. Armed with knowledge about the novel's world, Heli sets out on a quest to gather friends and past enemies to create a martial arts force strong enough to defy the fate he was given... or literally die trying.

(Source: Tapas)