Mai Tokiha

Also know as the "Meister of Tragedy" Mai was an extremely gifted Otome a few years prior to the show that mysteriously disappeared one day in the Sprites Forest. Before she disappeared she had been offered the position of being #4 of the Five Pillars, but it was said she had fallen in love with a young noble and was torn between the two dreams. She was Natsuki's rival from her days as a student and is Zipang's Tokiha Takumi's older sister.

She finally appears to Arika at the end of episode 22 and is living with the Cat Goddess, Mikoto, in the Black Valley. The valley is part of the Sprites Forest and actually exists in another dimension, though it frequently crosses over with her home world. It is later discovered that she never was actually torn between love and being an Otome, and had simply gotten lost while taking a walk and ended up in the Spirtes Forest. In the forest she is accidentally captured by one of Mikoto's food traps, and Mikoto accidentally swallows one of her Meister GEMs, making Mikoto her master.

In Mai-Otome Zwei, she still lives with Mikoto in the Black Valley, now called Mt. Nekogami, and has opened a Ramen shop in the newly formed town at the base of the mountain. Her GEM is known as the Fire Stirring Ruby. Her Element, Ignition, is still the same golden rings she had in My-HiME.

(Source: Wikipedia)