Ambrosius

Ambrosius (full name Ambrosius Melnuris) is a gray-haired, dark-skinned, bespectacled gentleman of indeterminate age, the second son of the Viscount Melnuris family and a mixed-blood member of the Edda, the world's supreme ruling race. Marked by the Edda's characteristic purple eyes, he keeps a vast, cathedral-like underground collector's room in the slums of Hydrangea, filled with dozens of bookshelves. He is famous as an eccentric, immensely wealthy book collector who deals in tomes rather than scrolls. Wof first meets him in the earliest arc when the witch Pakira brings Wof to trade a weapon encyclopedia for a herbology encyclopedia; Ambrosius casually calls Wof 'young man' (shounen-kun) and treats him with amused, unruffled courtesy.

Behind the mild scholar lies his true nature: Ambrosius is the transmigrated body of the King of Death's Darkness (the Dark Death King), one of the Death Kings who serve the dungeon goddess Yomido. In life he was originally a demon from another world, summoned into this world and discovered by Yomido, who made him a Death King; even after reincarnating as an Edda, Yomido let him remain the Dark Death King, an exceedingly rare case of a Death King retaining past-life memory. As a demon he honored the summoning contract of a man named Hargan, granting Hargan's wish to become the Wind Death King, which is why Ambrosius privately regards that 'small-fry' king as his own failed handiwork.

Personality-wise he is calm, ironic, and dryly witty, the unflappable 'adult' of any group. He and the Light Death King Shiro share a long, mutually wary acquaintance, trading barbed banter over tea and milk in his gallery. On the Forbidden Land expedition he joins Wof's party alongside Mineha, Narcissus and Megadia, coolly identifying ancient trees and parasitic worms, offering steady advice, and quietly helping transport and install a dungeon core; his knowledge and power repeatedly prove he is 'no ordinary man,' even when he deliberately keeps a low profile.

His identity is exposed to Wof by the goddess Yomido, after which Ambrosius and Shiro reluctantly confess the truth and pledge full cooperation with Wof's mission to find a successor for the vacant Wind Death King. He becomes a key advisor in the Wind Death King 'audition,' scouting property, evaluating candidates, and guiding Wof, though he is repeatedly overshadowed and teased as 'plain' by the louder Narcissus. He also accompanies Wof to meet the Water Death King, and remains an ally who long predates Wof's acquaintance with Pakira.