Boss, alternatively known as Don Bossman, leads the Bravery Quartet. He first emerges as a secondary antagonist in the Pompo Hills Arc, later reforming and becoming Alma's assistant.

He is an older man with a muscular build and above-average height. His attire consists of a white bodysuit marked by dark-red stripes, covered by red underwear featuring star patterns below the hems. Gold rings and gemstones adorn him, reflecting his affinity for jewelry. A long, collared red cape with yellow stars on the back and a matching dark-red pointed hat complete his flamboyant look. He wears black glasses and sports a single gold tooth. Two purple bat-wings and a zigzagged tail, manifestations of his curse, remain hidden beneath his hat.

His personality blends pride, flamboyance, and a love for theatrical entrances, often directing his group in elaborate poses. Despite an outwardly jovial manner, he exhibits mild abuse toward subordinates like Julivert when they make mistakes, though typically in a comedic context. He places supreme importance on bravery, frequently incorporating "brave" into his invented vocabulary. Ironically, Boss displays personal cowardice when directly threatened, though others' acts of valor can inspire courage in him.

He harbors deep resentment toward non-sorcerers, believing they exploit sorcerers only when convenient and discard them afterward. This worldview fuels his criminal actions against humans, including theft and violence—such as breaking a civilian's leg in the manga. He justifies these deeds as fair retribution for societal discrimination against sorcerers, whom he calls "birds of the same feather." However, witnessing genuine bravery, like Alma risking her life to save others, can sway his moral view, making him deem the exploitation of such individuals immoral.

In the Pompo Hills Arc, Boss and the Bravery Quartet arrive pretending to be heroes, rescuing civilians from a Nemesis attack—later revealed as a ruse to loot the town's bank. After Seth disrupts their scheme and a Nemesis threatens the bank, Boss attempts to flee with stolen riches but is captured by Alma. She imprisons the group in a parchment scroll; Boss devises an escape using Feathered Underwear to generate magic. Alma counters by wiping his memory temporarily with an Identity Substitution Potion, making him believe he is a chicken.

Manga and anime portrayals differ in his actions. In the manga, Boss directly causes a Nemesis egg to hatch prematurely by encouraging Seth to smash it and deceives villagers by falsely claiming gold grants invisibility to Nemeses. In the anime, the egg hatches independently, and his manipulation focuses on evacuating civilians under false pretenses. Post-arc, he reforms and becomes Alma's assistant, shifting from antagonist to ally.

Boss possesses significant physical strength, demonstrated by casually lifting large stone slabs, and notable durability, surviving brutal beatings from Seth. As a sorcerer, he wields destructive Fantasia-based beams—like his "Bravery Destroyer" spell—capable of repelling Nemeses. He commands knowledge of sealing spells and magical theory, expressing exasperation at unconventional spellcasting methods like Seth's barehanded magic. His expertise includes recognizing the importance of incantations and proper conduits for Fantasia manipulation, reflecting a structured approach to sorcery. This combination of physical prowess and magical acumen establishes him as a formidable figure within his group.