Hyeonjilmusin

Mok Hwi-Young, a prominent merchant of the Central Plains, is killed in an attack by the Demon Sect one day. Just as he believes he has died, he finds himself transported back to his childhood—some thirty years earlier—when he was training as a lay disciple at the Wudang Sect. Then, a mysterious bamboo tablet appears before Hwi-Young, offering to buy and sell martial arts talents... What will Mok Hwi-Young be able to accomplish now that he has returned to the Wudang Sect?

(Source: Naver, translated)