Emperor Heizei
Fine distinctions were collapsed or expanded in a gradual re-organization which became formalized during the Heian period. For example, in 806, Emperor Heizei elevated the former Fujiwara no Tarashiko (藤原帯子) (?-794), also known as Taishi, by giving her the Imperial title of "Kōgō" or empress. This occurred 12 years after her death, and it became the first time this posthumously elevated rank was bestowed.