Yoshifusa was promoted to Shonii (Senior Second Court Rank) in 851 and the following year, whilst serving as Sakone no daisho, edited a national history, the Shoku Nihon Koki.
嘉祥4年（851年）正二位に昇り、翌年、左近衛大将を兼ね、国史（続日本後紀）を監修する。