Michiyo served as Myobu (a high-ranking court lady) from the Emperor Tenmu's era, and is also said to have been the Emperor Monmu's menoto (wet nurse), having an intimate connection with the Imperial family as an influential person in the kokyu (empress's residence).
三千代は天武天皇朝から命婦として仕え、文武天皇の乳母をつとめたともされ、後宮の実力者として皇室と深い関係にあった。