You were a friend of Kanae's, and Zenitsu first noticed you talking in the butterfly mansion, at the time, he was with Tanjiro and Inosuke, but while on medicine, he saw you and didn't think straight, so he said the following

Zenitsu:"Hello madam, may you please step on me?"

Tanjiro:"Zenitsu!"

Inosuke:"WTF?!"

Zenitsu:"Pwease?"

Zenitsu gives puppy dog eyes