Don Bossman, known as Boss, leads the Bravery Quartet and emerges as a secondary antagonist in the Pompo Hills story. He stands as an older, muscular man of above-average height, boasting a flamboyant style: a white bodysuit with dark-red stripes, red star-patterned underwear, a long-collared red cape decorated with yellow stars, and a matching dark-red pointed hat. His accessories include black concealing glasses, a single gold tooth, and multiple gold rings and gemstones. Light brown shoes featuring bat-wing adornments complete his outfit. Two purple bat-wings sprout from his head, accompanied by a zigzag tail – visible signs of his curse – typically hidden beneath his hat.

His personality radiates pride and theatrical flair, often declaring his leadership during the Bravery Quartet's dramatic entrances. He exhibits occasional mild abuse towards subordinates like Julivert Jenoh, usually for comedic effect through choking or smacking them after errors. Boss champions an ideology centered on bravery, constantly coining new "brave"-prefixed vocabulary. Paradoxically, he flees from direct threats yet finds courage sparked by others' actions, like Alma's self-sacrifice. He justifies crimes against non-sorcerers as retaliation for society's discrimination against the infected, believing sorcerers deserve mutual loyalty as "birds of the same feather." However, he deems exploiting genuinely brave opponents immoral.

His involvement starts during Pompo Hills. In the anime, he arrives disguised as a rescuer, repelling a Nemesis with his "Bravery Destroyer" spell and directing civilians toward a "safe space" later revealed as a targeted bank. After confining the townspeople, he robs the institution and tries manipulating Seth with lectures on human-sorcerer conflict and stolen money, only to be punched. He escapes but is captured by Alma and imprisoned in a scroll. The manga diverges: he orchestrates a deception by falsely claiming gold grants invisibility to Nemeses, leveraging a civilian's leg injury to build trust. When Seth prematurely hatches a Nemesis egg, Boss exploits the chaos to loot gold reserves. Confronted by Seth, he is beaten and wielded as an improvised weapon against the Nemesis. Post-battle, Alma cages the quartet; Boss engineers an escape using Feathered Underwear but is subdued by an Identity Substitution Potion that temporarily convinces him he is a chicken.

Physically, he demonstrates notable strength, lifting large stone slabs, and durability sufficient to withstand Seth's assaults, though he fears Nemesis-level attacks. His sorcery includes ranged energy beams like Bravery Destroyer and knowledge of Fantasia manipulation, expressing frustration at Seth's unconventional spellcasting. He understands the importance of incantations and magical conduits like feather blades.