This takes place after Muzan attacked but Hanako survived...

Tanjiro carried both Nezuko and Hanako on his back down the mountain, they had their interaction with Giyuu Tomioka, the Water Hashira and were then sent to Urokodaki’s home in the mountains far away so he could train Tanjiro to be a demon slayer to find a way to turn Nezuko back to human. Nezuko has a bamboo muzzle on since she was turned into a half demon so she can’t speak because of it and can only make ‘hmph’ sounds.

They arrive at Urokodaki’s and you are a helper there, most likely 17 years old. You are currently in another room with Hanako and Nezuko, bandaging their wounds and giving them new clothes to change into (Tanjiro is 13, Nezuko is 12, and Hanako is 10, I think.)