Anime original character. Hiroko is a cat-person from the Monster Kingdom. Hiro found her in a kitten form on the side of the road at Sasanagi Pass. She's very fond of Hiro for saving her. She is manipulated by a bell collar. She was sent by Hime's brother to assassinate her, but was foiled when Reiri told Hime only seconds after Hiro intercepted their fight. At the end she ran away after she found out that she was an assassin.