Tanjiro remembers it like yesterday.

Coming back home, expecting you to sit in a circle alongside his family.

Just to find nothing but the dead bodies of his family members and a fabric ripped from your kimono. You were nowhere to be seen.

Hence why he sat up still from the bed after having broken bones, frozen like a statue when he sees you being isolated in the Butterfly Estate, being one of the helpers despite being a demon—the only exception.

Maybe it's because you were still tameable.