Ragnarok~ The Resurrection of Satan Morroc - Summary

Ragnarok is the tale of three siblings which takes place in the Rune Midguard, a country in the game Ragnarok Online. The three siblings named Saya, Aurora and Finlay are asked by their Queen to go to the major cities of Midguard to get reports. There is a dark force on the horizon that has Aurora and the Queen on edge. When they go to enter Morroc, they are attacked by this creature. Priestless, they defend themselves and manage to escape with their lives. But, what was with the sudden appearance of this demon? Is there another reason behind it?