The adventurers hear a strange story from the scouts of the Oscuras Residence while assisting Mirgandia on the continent of Freios. The scouts discovered a strange sound in the Monster Tree Hill across the Jade Forest which is waking up the dead soldiers buried in a nearby cemetary.
During the adventure, the adventurers end up meeting a mysterious creature named 'Lapidem'. Lapidem tells the adventurer that he's a reasonable rock that has been living to serve the ancient Gods and Goddesses by protecting the area. Lapidem never falls asleep but when he did fall asleep once, an unnatural monster have appeared out of nowhere and began screaming in the Monster Tree Hill.
This chaotic scream from a creature named "Arborum", begins to shake the creatures in the area. It even brought the dead back to life. Of course, they are reborn as evil, undead creatures.
For this reason, the adventurer gets on the move to defeat the "Arborum" that seems to have caused this problem.