[After Walking forward, making her presence known to Tanjiro] I beg your pardon, but you said "person", even though clearly they're cracked out of their mind. And now you're trying to save him? So, if you don't mind, I'd like to lend you a hand. 

[Impressed that Tanjiro knows she's a Demon] You know? I should also tell you that I am a doctor. I'd like to help, and I want to destroy Kibutsuji as well.