Nezuko Kamado, eldest daughter of the mountain-dwelling Kamado family, survives a demonic massacre orchestrated by Muzan Kibutsuji, who transforms her into a demon. Though her human memories fracture, remnants of familial bonds persist, anchoring her to older brother Tanjiro. He vows to cure her, embarking on a demon-slaying path while safeguarding her. Initially driven by primal bloodlust, Nezuko’s instincts shift upon witnessing Tanjiro’s protective resolve. She cultivates unwavering loyalty, suppressing her hunger through sleep rather than human consumption. A bamboo muzzle from demon slayer Giyu Tomioka prevents accidental harm, while hypnotic conditioning under Sakonji Urokodaki during a two-year hibernation reshapes her psyche: humans become family to protect, demons targets to destroy. This mental framework subdues her consciousness, prioritizing survival adaptations like sunlight resistance. Her demonic physiology grants rapid regeneration, strength, and body manipulation, enabling shifts between a childlike form for daylight travel in a wooden box and an adult combat state. The Blood Demon Art "Exploding Blood" manifests as pink flames ignited from her blood, searing demons and amplifying Tanjiro’s techniques—such as turning his blade crimson. In battles against foes like the Swamp Demon, Rui, and Daki, she adapts swiftly. A berserk state, marked by a horn and vine-like markings, unleashes devastating power but risks失控, nearly causing a human casualty in Yoshiwara until Tanjiro halts her. The Swordsmith Village arc triggers a pivotal mutation: sunlight exposure awakens immunity, a trait Muzan covets. This evolution partially restores her speech, fragmented from years of disuse. Later, Tamayo’s antidote, bolstered by allies, reverses her demonic traits, fully restoring humanity. Post-transformation, flame-orange hair tips remain, inherited by descendant Toko. Nezuko’s protective nature extends to allies like Mitsuri Kanroji, whom she treats as kin, engaging in playful interactions despite her demonic state. Her dynamic with Zenitsu Agatsuma matures from one-sided infatuation to mutual respect, eventually leading to marriage. In Muzan’s final defeat, her restored humanity proves vital as she shields others from a demonized Tanjiro. Post-war, she reclaims peace alongside surviving companions.