He is "Cocytus", imbued with the power of "Link Joker", the incarnation of "Void". He has fallen further to the bottom of darkness. Responding reluctantly to the rally of "Nightmist", Cocytus successfully repelled the surprise attack from the invaders. He was interested in the mysterious power with a different nature when compared to darkness and made futile attempts to analyze the remains of the invaders. Accidentally, the residue of "Void" residing inside the dead bodies was attracted by the extraordinarily negative emotion of the Necromancer, and they eventually combined within the soul and subconsciousness of Cocytus.
The King of Hades' Sea arises with an unrotting body and a fallen soul. Driven by undying abomination, he has found the power of Nothingness, which can devour even darkness itself. To imprison an unforgivable sinner named "The World" in a hollow prison in where nothing exists---Tonight, the lord of the ice prison lurks out from the gravely cold gate, accompanied by indefinite grudge and insanity.