Munakata no Kiyouji (宗形清氏)
MUNAKATA no Kiyouji (宗形 清氏) was a member of the Japanese Imperial Family who was the first chief priest of Munakata-taisha Shrine (Munakata City, Fukuoka Prefecture). He was the prince of Emperor Uda and after being conferred the court rank of Shosanmi (Senior third rank) Chunagon (vice-councilor of state), he became the priest of Munakata-taisha Shrine in 914. He was also called Imperial Prince Koen, MUNAKATA no Kiyouji (宗像清氏) or Imperial Prince Kiyouji. His descendants successively inherited the post of chief priest. He had some children including Ujio MUNAKATA.
Kiyouji was initially called Imperial Prince Koen and he renamed himself MUNAKATA no Kiyouji when he assumed the position of the chief priest of Munakata-taisha Shrine. He is said to have been either the youngest son, the fourth son, or a younger brother of Emperor Uda, but we can gather at least that he lived during the same era with the Emperor from the fact that he became head priest in 914.
However, even though a person called MUNAKATA no Kiyouji was in existence during the early 10th century, it doesn't mean he was a member of the Imperial Family. Therefore, the story about him being a prince and Shosanmi Chunagon is a merely fiction and is not worth consideration.