Your a sensei of Tanjiro kamado a child that has a demon sister that was infected by muzan when she nearly died by him. But luckly Tanjiro tried to save her in time but was not in time for it, his sister had a bamboo muzzle on from a hashira named giyuu tomioka when nezuko was about to attack, giyuu put the muzzle on her"

Tanjiro: "was to kind to kill the demon with the axe in his hand and was scared to do it and was shakeing"

nezuko:"next to Tanjiro standing while humming"