WEBOnmyōdō. Abe no Seimei, a famous onmyōji. Onmyōdō ( 陰陽道, also In'yōdō, lit.'The Way of Yin and Yang') is a technique that uses knowledge of astronomy and calendars to divine good fortune in terms of date, time, direction and general personnel affairs, originating from the philosophy of the yin-yang and the five elements. [1]