Mir's Legend - The Forgotten Ones미르의 전설 : 잊혀진 전사들

This is a story based off a popular chinese game. A party consisting of 5 powerful people are off on a quest to kill the Paragon Dragon that resides in the mountains. Not many facts are known about the area, except that there are mysteries of the past hidden with various monsters and demons guarding the place. What is the identity of the powerful force behind it?