She's Gon 

One day while playing videogames, a strange creature called Didi approaches Yu Yong Gi and claims he has a chance of becoming a Hero of 0.05%. And as such she has to aid him in becoming one. She starts showing him the evils of being a Hero, and after a while Yu Yong Gi realizes she is actually attempting to deter him from that path rather than aid him. With the cat out of the bag, she confesses she is a minion of the Dark Lord, meant to make sure he never wishes to become a Hero. Does the average Yu Yong Gi actually pose such a threat to the Devil Lords plans?