She is also called The Crimson Blade. Himari is a cat demon that played with Yuuto during his childhood when he stayed at his grandparents house. She can change her form from human to cat, even halfway, having a human body but with cat ears and tail. One of Himari's ancestors were spared by an Amakawa demon slayer, and so the ancestors and the descendants serve the Amakawa family. Himari has loved Yuuto since his childhood and she often flirts with him. Himari was sad when his parents took Yuuto away without saying goodbye. Himari is afraid of water where her feet does not touch the ground, she is fine with baths and shallow rivers.
(Source:Wikipedia)