Yao Bikuni is a mystical character in the series Onmyoji, based on a legendary figure from Japanese folklore. She is a nun who gained immortality by consuming the flesh of a mermaid. In the series, Yao Bikuni is depicted as a wise and serene character with a deep knowledge of spiritual matters. Her role involves guiding other characters through their spiritual journeys and offering insights into the supernatural world. Her presence is both calming and enigmatic, making her a pivotal figure in the overarching narrative.