all his life, choi siwoo’s complex was his fatness. even though he leaves his house to run and run until well past midnight, he was running and running until well past midnight after leaving his house, when he met an old man in the middle of the trail. in a blink of an eye, the old man swathes choi siwoo in the straw backpack he was carrying. the place choi siwoo was thrown into was the ruins of an enormous hanok. on the outskirts of the vast yard, there were countless black shadows standing around him in the middle of the yard he had fallen into. the old man spoke to choi siwoo, who was trembling without knowing why. once every 666 years, there’s a festival to choose the goblin king, and that the right to participate is given to each of the goblin clans that exist in the world. and that choi siwoo himself is a mixed blood of human and goblin, specifically of a goblin line that has now gone extinct, and that he is now the only one who can have the right to participate that’s given to the goblins. the only survivor who inherited the blood of goblins, the adventure of the half-monster boy choi siwoo begins.