Vulcan Joseph serves as chief engineer for Special Fire Force Company 8, celebrated for his mechanical brilliance and dedication to preserving life. His family engineered the Amaterasu reactor, a critical power source for the Tokyo Empire, but severed ties with Haijima Industries upon discovering its human energy source. After his father and grandfather suspiciously transformed into Infernals—events linked to Haijima and his father’s former apprentice Dr. Giovanni—Vulcan developed intense hatred toward the corporation and initially distrusted the Fire Force as Haijima subsidiaries. Standing 178 cm tall with an athletic build, he has short red hair with shaved sides and blue eyes. Distinctive black-striped tattoos adorn his body: two bands encircle his neck, three cross each shoulder, two mark each upper arm, and one appears on his left forearm. While working, he wears an eerie ram-skull mask with twisted horns and goggles, paired with dark trousers, a tool belt, and thick gloves. Animal motifs feature prominently in his attire, including a white shirt emblazoned with "THE ANIMAL" and a black paw print. Driven by engineering passion and profound love for animals, Vulcan dreams of creating a new energy source surpassing Amaterasu to resurrect extinct species and restore global ecosystems. His engineering philosophy prioritizes reliability; he tests inventions by smashing them to ensure they endure extreme conditions, declaring that "important things cannot be allowed to break." He maintains machines are mere tools, valuing faith in people and animals over mechanical dependence. Initially resistant to organizations, Vulcan resides in a junkyard workshop with apprentice Yū and sheltered fugitive Lisa Isaribi. When Company 8 members Shinra Kusakabe and Arthur Boyle seek his aid, he pelts them with cans but spares Iris, revealing his refusal to harm women. After witnessing Company 8 defend him from a White-Clad attack led by Giovanni—who sought the Amaterasu Key guarded by Vulcan’s family—he breaks his vow of independence to join Company 8, protecting his newfound family and confronting Giovanni. His hatred for Giovanni intensifies when the villain manipulates Lisa—a White-Clad operative codenamed Feeler—as a hostage. Forced to shoot Company 8 Captain Akitaru Ōbi to save Lisa, Vulcan outwits Giovanni by preemptively outfitting Ōbi with a bulletproof vest. After Giovanni abandons Lisa, Vulcan carries her to safety, solidifying their bond. He later helps her overcome her fear of Giovanni during their final clash. As Company 8’s engineer, Vulcan designs pivotal gear like Maki Oze’s aerial combat units "Iron Owls" and Arthur Boyle’s delusion-powered "Penguin Helmet." Though lacking pyrokinetic abilities, his physical strength from machinery work enables direct mission participation. He aids in rescuing Ōbi from the Tokyo Army and survives the Great Cataclysm after Shinra Kusakabe rewrites reality. Mythological and religious influences shape his background: "Vulcan" references the Roman god of fire and metalworking, while "Joseph" alludes to the biblical figure sold into slavery. His shoulder tattoos echo designs from Atsushi Ohkubo’s prior work *Soul Eater*.