Compared to her counterparts, Miime has a less human-like appearance including pale skin, long green hair, green eyes with no irises, a long and willowy body, a visible mouth, and pointy ears. She is usually seen in a green dress with white decorations.
Miime is a calm and compassionate person who stands as being the most loyal of Harlock's crew, going along with Harlock's plans for the universe in spite of knowing its self-destructive nature. Miime has faith that events that take place can help for the better and that as long as the Arcadia runs, truth and freedom can be achieved.
As a Nibelung, Miime has an extremely long lifespan that allows her to survive for centuries. She appears to be tied to dark matter and possesses advanced technology that allows it to be used as an energy source. As long as the Arcadia is able to function with a captain, Miime is essentially immortal due to her connection with the dark matter and the ship. If this is in any way compromised, Miime will disappear.
Miime had met Harlock and Tochiro Oyama a century before the film's beginning as a supplier of dark matter technology. Miime would see the rise and fall of Harlock and Tochiro with Harlock becoming immortal from a dark matter out pour that made Earth uninhabitable and Tochiro's consciousness fusing with a ship's CPU as his body became damaged from an accident. Miime would join Harlock on the ship that became the Arcadia; going along with his plans, hoping that one day Harlock will have what he really seeks.
That day would come with the appearance of Yama, a Gaia Sanction spy whose loyalty has been tested back and forth as helped the crew but later arrested them upon finding out Harlock's plans to destroy the universe. Miime was imprisoned in a cell separate from everyone until Yama broke them all out with a sign of hope that showed that Earth can prosper again. Miime had helped get the Arcadia free as the crew showed the Gaia Sanction's cover-ups and also pushing the dark matter to its limit to shield itself from the Jovian Blaster. Miime had seemed to have been consumed by the engines because of this but had later reappeared as Yama was appointed as the new captain as the Arcadia began to run again.