Nope. Nezuko is the sister of the hero in Demon Slayer (the English title of Kimetsu no Yaiba). She has been transformed into a demon but retains her human personality and helps her brother, Tanjiro, hunt down other demons. She wears the bamboo gag to avoid biting someone and developing a taste for human flesh. Tanjiro also has to carry her around in a box because sunlight destroys demons.
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INHO, she is a woefully underdeveloped character given the potential of her dual nature. As someone else said, after the first couple of episodes, she pretty much just a Pokemon, popping out her box whenever she's needed to fight.
Still, she is a very popular character.
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Yet there is so much more potential.
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BTW, you can buy the bamboo gag online.
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