Katsuragi Kuon

The offspring of a forced union between Katsuragi Kimihiro's younger sister and a demon fox, Kimihiro freed her from the cult's clutches and raised her as his adoptive daughter. Although she should have been eliminated because of her demonic lineage, Kimihiro could not bring himself to kill his sister's child and decided to raise her as a human. The Onmyouji training and the medicine are meant to prevent her from manifesting her demon powers.

She's trained to use her talismans to summon fire to destroy evil spirits and demons. When her demonic powers awaken and she loses control, she uses lightning spells instead. The medicine she regularly imbibes is meant to shackle her innate demonic powers, not consuming it for two days coupled with repeated sexual intercourse is enough to make her lose control.