Emperor Seiwa
In the court of Emperor Seiwa, Koreyoshi continued his role as a teacher and now governor of Harima Province, and was promoted to . Passing through a number of other positions, including as director of the "Gyōbu-shō", he was in 870 appointed as vice-minister of the "Shikibu-shō". In 872, he joined the ranks of the "kugyō" with a promotion to "sangi". In 873 he was promoted to and in 879 to . In 880, Koreyoshi died at the age of 69.