Seiko Ayase

A spirit medium who goes by the name Santa Dodoria and Momo Ayase's grandmother, whom she lives with, despite appearing to be in her 20s. She helps Ayase and Okarun deal with dangerous spirits and yokai. Though she has no innate powers, she has an extensive knowledge of supernatural entities and curses, and uses various artifacts and the borrowed power of the god residing in their city to seal and exorcise yokai, though this power is only limited to the city itself.

(Source: Dandadan Wiki)