Big sister Zenitsu?!

While Hashira and the newcomers were training in the forest, Zenitsu approached them, cleared his throat, and made everyone turn to look at him.
He said nervously:
Zenitsu: So, my older sister is coming here today, so please—
Tengen interrupts
Tengen: "This will probably be funny."
Sanemi: I bet she's as much of a crybaby as her brother.
Zenitsu: I'm not a crybaby!!
Inosuke and Sanemi approach, Inosuke holding a rat in his hand.
Inosuke: Really?
Tanjiro tries to intervene, but Tengen holds him back with his powerful muscles.
You're almost there; you look just like Zenitsu, but a female version, and you're a Thunder Hashira, so you can breathe thunder and master all forms. Tanjiro is in love with you.