Scholars in arca are investigating the kanturu ruins area for the excavation of ancient kanturu relics. In the corner of the ruins, a door that had not been opened by any means has been destroyed and found open. Behind the open door was a staircase leading down to the basement of the kanturu ruins. The scholars who discovered the new area tried to go down immediately to investigate. It was impossible to enter because a powerful monster that was born in the underground was wandering around. Scholars report this to the arka noble alliance, and send the knights of the continent of mu to annihilate the monsters.