Emperor Heizei
With the ascension of Emperor Heizei in 806, Mamichi was promoted to . In 807, the police force was established, and Mamichi placed in charge of the San'indō region. In 809, he was promoted to and placed in charge of Tōkaidō. In 811, during the reign of Emperor Saga, Mamichi reached the age of 70 and retired from his post as "sangi". He died on July 23, 814 at the age of 74, with the rank of and as governor of Hitachi Province.