Tanjiro Kamado, eldest son of a mountain-dwelling charcoal-burning family in Taisho-era Japan, shouldered responsibility for his household after his father’s passing, selling charcoal to sustain his siblings and mother. A fateful snowstorm stranded him overnight, sparing him from a demonic massacre that claimed his family and left his sister Nezuko transformed into a demon. Driven by grief and resolve, he joined the Demon Slayer Corps to avenge his kin and restore Nezuko’s humanity. Under the tutelage of Sakonji Urokodaki, a retired Water Hashira, Tanjiro honed Water Breathing techniques, mirroring the fluidity of water in his swordsmanship. Surviving Final Selection by defeating the Hand Demon awakened a scar on his forehead, which later flared into a flame-patterned Demon Slayer Mark during intense combat, amplifying his strength. His standard black Nichirin blade intermittently shifted crimson, gaining potency to suppress demon regeneration. A clash with Lower Rank demon Rui unlocked latent memories of his father’s ceremonial Dance of the Fire God (Hinokami Kagura), an archaic Sun Breathing style. Despite its grueling physical toll, Tanjiro integrated this technique into his arsenal, later blending it with Water Breathing to conserve stamina during prolonged battles, such as his coordinated assault on Upper Rank Six siblings Gyutaro and Daki. Disguised as a courtesan in Yoshiwara’s Entertainment District alongside sound Hashira Tengen Uzui, Tanjiro uncovered demonic activity plaguing the region. The confrontation with Daki and Gyutaro tested his mastery of Sun Breathing, heightened olfactory senses, and synergy with Nezuko’s explosive Blood Demon Art, culminating in victory that pushed his endurance to its limits. Advancing to the Swordsmith Village, Tanjiro’s Demon Slayer Mark expanded, and his blade permanently adopted a crimson hue. During the climactic Infinity Castle siege against Muzan Kibutsuji, he deployed Sun Breathing’s Thirteenth Form—a sequence targeting the progenitor demon’s vital cells. Muzan’s final curse briefly transformed Tanjiro into a demon, halted only by Nezuko’s sacrifice and human allies’ swift intervention. His bonds defined his journey: unwavering loyalty to Nezuko, reverence for mentors Giyu Tomioka and Kyojuro Rengoku, and fierce camaraderie with Zenitsu and Inosuke. Though empathetic even to demons like Tamayo and Yushiro, he remained unyielding against those preying on the innocent. Physical evolution mirrored his growth: training trimmed his once-unruly hair, and the Demon Slayer uniform replaced rustic attire, though he retained his father’s hanafuda earrings. His acute sense of smell detected enemy weak points as “Opening Threads,” while tactical ingenuity and relentless spirit cemented his role in eradicating the demon scourge.