Nezuko Kamado, eldest daughter of a mountain-dwelling family, assisted her mother with siblings while her brother Tanjiro sold charcoal. Muzan Kibutsuji slaughtered her family, ending her human life and forcibly transforming her into a demon. Despite initial bloodlust, she resisted attacking Tanjiro and instead protected him from the Water Hashira Giyu Tomioka, establishing her unique demonic nature. Giyu provided a bamboo muzzle to suppress her urges and directed the siblings to Sakonji Urokodaki. During Tanjiro's two-year training, Urokodaki implanted hypnotic suggestions reinforcing that all humans are family to protect and all demons are enemies to eliminate. This conditioning bypassed her need for human flesh, allowing her to regain strength through prolonged sleep. Her physiology exhibited rapid growth without consuming humans, enhancing her physical capabilities in combat. Her physical traits include fair skin, long black hair fading to orange at the tips, sharp stiletto nails, and pink eyes with slit pupils. She wears a pink-patterned kimono and a dark brown haori. In battle, she employs superhuman strength, regenerative healing, and body manipulation—shrinking to fit in a transport box or enlarging during transformations. Her Blood Demon Art, Exploding Blood, ignites her blood into pink flames harmful only to demons, first manifested against Lower Rank Five Rui to sever his threads. In the Entertainment District Arc, her abilities expanded significantly. During the fight against Upper Rank Six Daki, she awakened a berserk state marked by heightened aggression, a white horn protruding from her forehead, crack-patterned skin, and prominent vein-like markings. This form amplified her speed and strength, enabling her to overpower Daki. Prolonged demonic rage eroded her humanity, culminating in an attack on a wounded human. Tanjiro intervened, singing a childhood lullaby to restore her control. Later, she used her blood flames to purge lethal poison from injured Demon Slayers, including Tengen Uzui and his allies, countering toxins from Daki's brother Gyutaro. Subsequent arcs revealed further evolution. She developed immunity to sunlight during the Swordsmith Village Arc. Her berserk form became controllable against Upper Rank Four Hantengu's clones. Eventually, she reverted to human via Tamayo's experimental drug, retaining orange-tipped hair as seen in her descendant Toko. Post-transformation, her speech improved gradually, initially hindered by years of muteness from the bamboo muzzle. Her bond with Tanjiro remains central, driving mutual protection—she shielded him from demon Tanjiro during the finale. Zenitsu Agatsuma displays romantic affection toward her; she often responds with detached curiosity or confusion, once mistaking him for Inosuke. Inosuke Hashibira initially distrusted her demonic nature but later accepted her, even teaching her to mispronounce his name. The Hashira acknowledged her after she resisted Sanemi Shinazugawa's Marechi blood and aided in critical battles.