WARNING: The following contains spoilers for Demon Slayer: Kimetsu no Yaiba Season 2, Episode 14, "Transformation," now streaming on Funimation, Hulu and Crunchyroll.
The most unique demon in all of Demon Slayer: Kimetsu no Yaiba, Nezuko Kamado, never fails to surprise. The only demon in the series who doesn't consume human flesh, Nezuko is proof that demons don't have to be evil -- or at least, she used to be. After the debut of her Berserker Form, Nezuko almost crossed the bright line in the sand on which her continued existence depends by attacking a human. If Nezuko is susceptible to the need to eat humans, could she be vulnerable to Muzan Kibutsuji's influence? After all, the Progenitor of Demons could use a new Upper-Moon after Akaza failed him and Daki proved to be laughably weak.
Seeing Tanjiro so heavily wounded after his fight with Daki, Nezuko was forced to remember the slaughter that took her family's lives and turned her into a demon. Pushed into an all-consuming rage, Nezuko transformed into a grown adult with vine tattoos on her body and a jagged horn on her head. In this state, referred to as her Berserker Form, she easily overpowered Daki, who holds the rank of Upper-Moon Six (a title she shares with her brother). Nezuko's raw power is undeniable as she bludgeoned Daki to pieces before burning her almost beyond repair with her Blood Demon Art, Pyrokinesis.
Earlier in the "Entertainment District" arc, Muzan instructed Daki to find and eliminate Nezuko because she had somehow escaped his control. However, now that Kibutsuji knows just how powerful Nezuko is -- because Muzan knows everything his demons know -- he might decide that Nezuko could be of great use to him. Nezuko is at least stronger than Daki, meaning that if Muzan could bring her back under his control, she would certainly qualify for the most prestigious title a demon can hold: a member of the Twelve Kizuki. Thanks to Nezuko's remarkable strength, she would have to be an Upper-Moon.
Granted, Nezuko's Blood Demon Art isn't very useful in this scenario given that it only harms other demons, and Muzan would prefer that they attack humans, not each other. No one truly knows what Muzan is capable of, but surely altering a demon's Blood Demon Art shouldn't be beyond his power. Nezuko's Pyrokinesis aside, her viciously sharp claws slice through flesh like butter, and her powerful kicks can even obliterate an Upper-Moon, so she's far from harmless.
Nezuko's most remarkable new ability is that she can solidify her blood to reassemble her dismembered body, possibly even to the extent that she could survive decapitation. A demon can only die from decapitation if it's done with a Nichirin Blade, but as Daki showed when she survived Tengen Uzui's killing blow, there are ways a demon can survive even that. It's unclear if Nezuko would have survived her decapitation if it had been a Nichirin Blade rather than Daki's belt, but surely if Daki can do it, so can Nezuko. What’s more, Nezuko can still control her dismembered body when connected by congealed blood, meaning she wouldn't even be vulnerable to a second strike after a successful decapitation.
One thing that's been made clear is that Nezuko is not herself when in this Berserker State, and if she's vulnerable to demonic bloodlust, she might be in danger of being susceptible to Muzan's control. Demon Slayer needs a fresh storyline once the "Entertainment District" arc wraps up, considering this is the second story arc in a row in which Tanjiro and the others must depend on a Hashira to save the day from an Upper-Moon. As the series comes dangerously close to spinning its wheels, Nezuko falling under Muzan's control would be the perfect way to shake things up in a personal way for our heroes.
