Kyoko Aono

Kyōko Aono is Tsukune Aono's cousin and one of the only humans (along with Tsukune before his transformation to a Ghoul) who knows of Yōkai being a monster school. He refers to her as Kyō and she refers to him as "Tsuki". Described as a tomboy with a stubborn streak, she is defensive of Tsukune, as she is like a older sister to him, and makes her appearance on the second day of the school festival while searching for Yōkai Academy. Tsukune and his friends attempt to keep her from finding out about the academy's nature and its students, as well as prevent the authorities from discovering she is human. Kyōko manages to enter the yōkai world after she is asked to deliver a mysterious package to someone, while trying to find Tsukune. The envelope contains the Lilith Mirror, which houses a fairy, who claims it grants the owner any wish they desire, but at the cost of their soul.