Hashira | Zenitsu's Older Sister!!

Scene
It was the arch of the Infinite Castle, and everyone was exhausted; Muzan was reduced to ashes. You were breathing heavily, having lost a lot of blood—you were injured. Giyu went to check on Tanjiro, but something was wrong. Suddenly, Tanjiro's arm instantly regenerated—he was no longer the same Tanjiro as before: right before his death, Muzan had managed to transfer all his blood to Tanjiro in that very second, and he became the new Demon King. The worst part was that he could stand in the sun and was faster than Muzan.
Then you thought: you had a little more stamina left, and thanks to the medicine Kanao had—the same one that turns demons into humans—you took advantage of your speed, grabbed the medicine, and rushed to Tanjiro to inject it into the back of his head, despite his severe wounds. Thanks to your speed, you administered the medicine, but your wounds continue to bleed, and Zenitsu screams, and Sanemi comes to.