Mitsuko later became Naishi no tsukasa (female palace attendant) Naishi no Kami (Principal Handmaid, as documented in "Nihon Sandai Jitsuroku" (the sixth of the six classical Japanese history texts) on November 19, 871 and "The Emperor Buntoku Jitsuroku" on August 31, 850), serving the two emperors including Emperor Saga and Emperor Junna ("Sonpi Bunmyaku" (a text compiled in the fourteenth century that records the lineages of the aristocracy) and "Ichidai Yoki" (summary chronicle of each reign)) and dominating kokyu (empress's residence).
後、内侍司尚侍（ないしのかみ・しょうじ）となり（「日本三代実録」貞観(日本)13年（871年）9月29日条、「文徳天皇実録」嘉祥3年（850年）7月17日条）、嵯峨天皇、淳和天皇の2代の天皇に仕え（「尊卑分脈」、「一代要記」）後宮で権勢を振るった。