Nezuko Kamado grew up in a charcoal-making family on Mount Kumatori, where she embraced her role as the eldest daughter by assisting her mother with chores and nurturing her younger siblings. Their tight-knit household, rooted in kindness, cultivated her compassionate spirit. Her peaceful existence crumbled when Muzan Kibutsuji slaughtered her family and transformed her into a demon, sparing only her and her brother Tanjiro. Though demonized, fractured memories of her human life anchored her determination to defend humanity rather than join their predators. Defying typical demon behavior, Nezuko sustained herself through sleep instead of consuming humans. Giyu Tomioka’s bamboo muzzle restrained her bite, though she broke free during crises. Her demonic traits granted superhuman speed, strength, and regeneration, alongside the ability to shrink into a child-sized form for agility or expand into a combat-ready adult stature—a shift that depleted her stamina. Her Blood Demon Art, "Exploding Blood," generated fiery flames lethal to demons, complementing Tanjiro’s Dance of the Flame God in battle. Confronting foes like the Swamp Demon and Upper Rank Six Daki, she displayed rapid adaptive growth. In her Advanced Demon Form—marked by a white horn, vine-like tattoos, and heightened power—she briefly succumbed to bloodlust until Tanjiro’s childhood lullaby grounded her, enabling mastery over this state. A turning point emerged against Hantengu when Nezuko spontaneously resisted sunlight, a universal demon weakness. This "Sunlight Immunity," derived from physiological adaptation rather than conscious effort per Tamayo’s analysis, made her Muzan’s prime target. Gradually, sunlight exposure and camaraderie restored her speech, muted by years of silence and the muzzle. Post-transformation, Nezuko’s emotions grew distant, yet Sakonji Urokodaki’s hypnosis during hibernation preserved her core empathy. She guarded humans as kin, attacking threatening demons and occasionally projecting sibling bonds onto allies like Yushiro. Even when tempted by Marechi blood, her will barred harm to humans, and she repeatedly risked herself to protect others, including intercepting lethal strikes aimed at Inosuke and Tanjiro. In Muzan’s final defeat, medical aid and Nezuko’s resilience restored her humanity. Though her human form returned, flame-tipped hair endured, later inherited by her descendant Toko. Her legacy persisted through marriage to Tanjiro’s descendant, cementing the bond forged through shared trials.