Hotaru Haganezuka, a swordsmith of the Swordsmith Village’s Haganezuka Clan, inherits a legacy of forging Nichirin blades for the Demon Slayer Corps. His fiery temperament sparked turmoil in early childhood, prompting his parents to relinquish caregiving duties by age two. Raised under village chief Tecchin Tecchikawahara, he received the name “Hotaru” (firefly)—a moniker he despises for its whimsical connotations. Concealed beneath a Hyottoko mask and headscarf, his attire blends practicality and eccentricity: a sunflower-patterned haori, a straw hat dangling wind chimes, and loose black garments. After enduring grueling mountain training and surviving Gyokko’s assault during the Swordsmith Village Arc, his physique sharpens into muscular definition. The battle scars him with an X-shaped gash across his face, a missing left eye, and unmasked features revealing long black hair, piercing eyes, and bold eyebrows. Obsession defines him. He hones blades with reckless devotion, undeterred by demonic threats or grave injuries—even Gyokko’s ambush failed to interrupt his sharpening of a centuries-old sword. Destruction of his creations triggers volcanic rage, often directed at Tanjiro Kamado through violent threats. Yet these outbursts dissolve into dark comedy: mitarashi dango pacifies his fury, while tickling subdues his tantrums. Beneath his abrasive exterior lies reverence for Demon Slayers. He fiercely defends their valor against criticism, and his bond with Tanjiro shifts from exasperation to grudging respect after overhearing the swordsmiths’ sacrifices acknowledged. This sparks his relentless effort to reforge a relic blade for Tanjiro, laboring through physical agony and peril. Mastering ancestral techniques, he wields lethal sharpening methods that demand unwavering focus—a test few smiths survive. His Tantōjutsu skill surfaces in frenzied knife attacks during clashes with Tanjiro. As demonic threats wane, his craft’s future grows uncertain, yet his dedication persists. Notable quirks include loathing his name, cherishing childhood wind chimes, and ambiguous marital status—contradicted between omake humor and canon. Hotaru’s legacy intertwines artisan pride, flawed humanity, and unyielding loyalty, reflecting the silent labor upholding the Demon Slayer Corps’ resolve.