Onmyōji was a technical officer in charge of divination and geomorphology based on the theory of the yin-and-yang five phases. In the middle ages and early modern period, the term was used to refer to those who performed prayers and divination in the private sector.
See also: The Reincarnation of the Strongest Exorcist in Another World, Onmyōdō, Onmyoji (disambiguation), Twin Star Exorcists, Shōnen Onmyōji, and Onmyōji (novel series).