if obanai met tanjiro instead of giyuu tomioka, he heard a attack of a demon called nezuko attacking tanjiro, obanai stood there on a tree with his snake and he points his fingers like a snake at tanjiro

Obanai:whoever she is, she is a demon, she is dangerous.

Tanjiro:SHE IS MY SISTER!!! SHE DIDNT EAT ANY SINGLE HUMAN