Warning: Contains spoilers for Demon Slayer: Kimetsu no Yaiba season 2 finale.
How was Nezuko able to heal Inosuke and Tengen in the Demon Slayer: Kimetsu no Yaiba season 2 finale? Throughout the series, Nezuko has gained a lot of different abilities, including a new transformation that puts her on the same level as an Upper Rank Kizuki. Her powers are some of the more varied in the series, and one specific ability was the key to saving Inosuke and Tengen.
Over the course of the fight against Daki and Gyutaro in season 2, the characters are infected by Gyutaro’s poisonous blood that slowly weakens and kills them over the course of the fight. Even after the two of them are defeated, the poison doesn't go away, and for Inosuke and Tengen, who have each taken on a large amount of poison, it looks as if they are both going to die. Fortunately, Nezuko is able to intervene and rid their bodies of the poison to save their lives.
Nezuko was able to heal them thanks to the use of her Blood Demon Art: Exploding Blood. Nezuko first unlocked Exploding Blood during Tanjiro’s fight with Lower Rank Kizuki Rui, and it has the power to turn her blood into a fire that burns demons, and only demons. Thanks to that, Nezuko was able to burn away the poison inside of Inosuke and Tengen without hurting them any more than they already were.
Nezuko being able to use Exploding Blood non-offensively had already been shown in the “Mugen Train” arc. During that arc, Nezuko used Exploding Blood on Tanjiro to help snap him out of the dream Enmu had trapped him in, and she later used it to help wake up Zenitsu, Inosuke, and Rengoku, as well. Her powers had already been established to have a use outside of fighting, and the “Entertainment District” arc further expands on that with how they’re used to save the lives of Inosuke and Tengen’s lives.
Nezuko being able to use Exploding Blood to heal people has a lot of implications for her future involvement in Demon Slayer. Since Demon Slayers are all just humans, they always have to recover from injuries the way a normal human would, no matter how long it takes. With Nezuko’s Blood Demon Art, however, there’s now an easy means to deal with demons who, like Gyutaro, fight with poison or anything that involves attacking the body internally. Not only that, but since demons are born from a human physically taking in Muzan’s blood, it’s possible that Nezuko’s powers could also be used to stop someone from turning into a demon. All in all, Nezuko has been set up as a powerful countermeasure for Muzan and his demons, and it’ll be interesting to see how Demon Slayer: Kimetsu no Yaiba handles that.
