Archduke Gunther is one of the heads of the Seven Great Nobles (a.k.a. Seven Celestial Sages) that serves Ruminas. He is a True Ancestor Vampire who has lived since ancient times and has surpassed a simple Demon Lord. His ability can be equaled to that of Karion, a former Demon Lord.
When pressed into a corner, Gunther reveals the red eyes and sharp teeth typical of his species, even though he's long evolved beyond the need to drink blood.
Gunther frequently quarrels with his fellow nobles.
Despite having long evolved beyond the need to drink blood, he shows his savage old self when pressed, his self as the Emperor of the Night.
As an Archduke Class Vampire Noble, Gunther's ability is comparable to Karion's, he possesses high regeneration capability and has evolved to the point where he can absorb Mana from his surroundings, thus eliminating any need to drink blood.