Tanjiro Kamado came from a rural mountain family of charcoal sellers. After his father's death, he supported his mother and five younger siblings, shouldering responsibilities early. A distinctive forehead scar marked where he protected his brother from a boiling pot. This peaceful life shattered when the demon Muzan Kibutsuji slaughtered his family, leaving only his sister Nezuko alive yet transformed into a demon. The demon slayer Giyu Tomioka encountered them during Nezuko's first demonic outbreak. Though Giyu intended to kill Nezuko, witnessing her protect Tanjiro and resist harming humans led him to spare her. He directed Tanjiro to train under Sakonji Urokodaki at Mount Sagiri. Tanjiro underwent two years of rigorous training, developing physical strength, endurance, and swordsmanship fundamentals. He passed the Final Selection by defeating the Hand Demon, receiving a Nichirin sword that turned black—a rare color. His forehead scar also transformed into a flame-like pattern during this trial. He travels carrying Nezuko in a specially designed wooden box to shield her from sunlight. His standard attire is the demon slayer uniform—a dark gakuran jacket, baggy pants, and white calf-wraps—topped by his signature black-and-sea-green checkered haori. He wears hanafuda earrings depicting a rising sun, a family heirloom later revealed to hold significance to Muzan and the Sun Breathing legacy. Tanjiro exhibits profound kindness and empathy, often praying for defeated demons and acknowledging their lost humanity. This contrasts with intense determination to protect the vulnerable and deep-seated rage against cruelty, especially towards Muzan and demons harming innocents. He displays low tolerance for cowardice or rudeness, frequently clashing with comrades Zenitsu Agatsuma over fearfulness and Inosuke Hashibira over aggression. His honesty makes deception physically taxing, causing visible facial contortions when attempting lies. Key abilities include an extraordinary sense of smell, detecting emotions, environmental changes, and combat openings like an enemy's "opening thread." He mastered Water Breathing under Urokodaki and later integrated the Hinokami Kagura (Dance of the Fire God), a Sun Breathing derivative passed down through his family. Combining this technique with Total Concentration Breathing enhances his physical capabilities, enabling high-speed combat and powerful strikes. Additional traits include exceptional stamina, tactical intuition, and a notably resilient skull used effectively in headbutts. During the Mugen Train mission, Tanjiro joined the Flame Hashira Kyojuro Rengoku against Enmu, Lower Rank One of the Twelve Kizuki. After falling into a dream enchantment, he awakened through Nezuko's intervention and his father's spiritual guidance. He cooperated with Inosuke to sever Enmu's neck, fused with the train. Following Enmu's defeat, Upper Rank Three Akaza attacked, leading to Rengoku's fatal battle. Tanjiro witnessed Rengoku's death, denounced Akaza's retreat as cowardice, and absorbed Rengoku's final encouragement to persevere. Later developments include achieving a Demon Slayer Mark during battles against Upper Ranks, signified by his scar expanding into a flame-like pattern. He confronted Muzan in a prolonged battle, suffering severe injuries including the loss of his right eye and left arm. As Muzan died, he injected Tanjiro with blood to transform him into the ultimate demon. Tanjiro temporarily lost control, attacking allies until Nezuko and others reversed his transformation. This resulted in permanent physical changes: blindness in his right eye and a withered, minimally functional left arm. Post-war, he married fellow demon slayer Kanao Tsuyuri. His lineage connects to Sun Breathing through his ancestor Sumiyoshi, who learned it directly from Yoriichi Tsugikuni. The Kamado family preserved this legacy through ritual dances and the hanafuda earrings, enabling Tanjiro to access its techniques.