Standard Yamataian sizes with gray eyes, long black hair, and white skin.
Mayumi is driven by efficiency and punctuality. Most find her difficult to get along with and to be cold. She has a tendency to be overly analytical of others actions and personalities and is often suspicious. Mayumi graduated the same year as Taisho Ketsurui-Motoyoshi Katsuko, from the War College at Kyoto, and has been a trusted friend and confident to the Taisho over the years. When Ketsurui-Motoyoshi Katsuko was murdered she was promoted to Taisho and made commanding officer of the Fifth Expeditionary Fleet.
In YE 29 Mayumi stepped down to allow Motoyoshi Katsuko to become Taisho of the fleet again. Mayumi retired from the Star Army of Yamatai to pursue a future with NovaCorp as the Director of its subsidiary company, Motoyoshi Fleet Yards.