No one knows why but there was once a time when Earth made such a loud sneeze that millions went deaf, and a dungeon popped up out of nowhere. It was filled with monsters, riches, and death.

A hundred years later a person known as Terax stood beside the bed of his dying father. He gave Terax a golden pendant and told him that, "You must head for the dungeon, because..." And with that, his father passed away before telling him the reason. 

That pissed Terax off, so he headed to the dungeon to find out what his father wanted to tell him.