kamado nezuko
A main character from Kimetsu no Yaiba and the sister of Kamado Tanjirou. She was a human before getting exposed to demon blood into her veins, eventually turning into a demon when her brother found her.
She has pink eyes and long black and brown hair and is often seen wearing a kimono and a bamboo muzzle around her mouth like a bit gag.
When she goes into her "demon form", her eyebrows point downward with veins all around her head visible and stretching her skin and her pupils turn different. In this form she has a single horn but not the bamboo muzzle on.