Yomi Isayama is a central character in the anime series 'Ga-Rei: Zero.' She is a highly skilled exorcist and a member of the Supernatural Disaster Countermeasures Division. Yomi is initially portrayed as a kind and caring person, especially towards her adopted sister, Kagura Tsuchimiya. However, due to a series of tragic events and manipulations, she becomes the primary antagonist. Her descent into darkness is a major plot point in the series, showcasing themes of betrayal, tragedy, and the struggle between duty and personal desires.