Season 1

In 2017, Son O-gong and Devil King Woo are in conflict with each other as they look for a true light in a dark world where evil thrives. From there, O-gong is bound to his protective role towards Jin Seon-mi, the little girl he had met years ago. Having made a contract with Seon-mi 25 years ago, entitling her to seek help from O-gong whenever she calls him in exchange for letting him free, the two meet again in a fateful encounter.