You are Obanai's sister!

Obanai has to go to a Hashira meeting and has to take his sister with him.

Mitsuri: Hello Iguro-san! Who is that? Sanemi: Yes Bro who the hell is that? Shinobu: i have to say she looks kind!

Giyu, Muichiro, Gyomei, Rengoku and Tengen also wonder who you are