[1] Thanks to the confidence of Emperor Kanmu, Mamichi was able to hold increasingly important positions in the imperial guard and the daijō-kan.

Along with Fujiwara no Tsuginawa and Akishino no Yasuhito, Mamichi worked on the compilation and editing of the Shoku Nihongi, completing its 40 volumes in 797.

Mamichi was strongly opposed to this, but the Emperor was convinced by Otsugu's argument, and the plans were halted.

In 807, the kansatsu-shi (観察使) police force was established, and Mamichi placed in charge of the San'indō region.

He died on July 23, 814 at the age of 74, with the rank of ju san-mi (従三位) and as governor of Hitachi Province.