The Demon King is considered an ancient threat to the world, although it isn't known how long he is already reigning in Rhir. He might be one of the few Immortals of the Innworld, as his lifespan was compared to that of Belavierr who is over a thousand years old.
Two famous champions of the Demon King, a [Mage] Demon and an [Archer] Demon both over level 40, invaded Paranfer with a small army of Fearless in the same year that the Earthworlders were summoned. Tom killed the [Archer], while the [Mage] could escape. To get into the capital of the kingdom, the Demon King conspired with the Fool.
Powers and Abilities
His classes remain unknown, he might or might not be an actual [King].