Mai Tokiha vanished mysteriously before My-Otome Zwei, her unexplained absence from Garderobe Academy spawning the legend of the "Tragic Meister," fueled by Headmistress Natsuki Kruger's attempts to explain her disappearance. A princess of Zipang, Mai left her homeland without authorization, enrolling at Garderobe under a wealthy family's sponsorship while concealing her royal status. She rose to become the #1 ranked Coral student, sharing a room and forging a close friendship with academic rival Natsuki Kruger, the #2 Coral. Achieving Pearl #1 rank, she faced a graduation dilemma: joining Garderobe's Five Columns or serving her sponsors as an Otome, while desiring to aid her younger brother Takumi Tokiha, Zipang's future leader. During a walk to consider her choices, she fell into one of Mikoto's traps in Sprites Forest. Mikoto accidentally swallowed Mai's Meister GEM, the Fire Stirring Ruby, creating an unofficial contract and trapping Mai in the Black Valley dimension.

Residing in the Black Valley (later Mt. Nekogami) with Mikoto as her Otome in My-Otome Zwei, Mai operates a ramen shop at the mountain's base frequented by Queen Mashiro Blan de Windbloom for meals and counsel. Following an argument between Mashiro and Arika Yumemiya, Mai mentors both: she guides Mashiro on leadership and queenship using her royal background, and provides Arika with combat training, cooking lessons, and emotional support, treating her like a younger sister. Mai actively combats powerful Slaves and Nagi's forces, notably destroying a large portion of an enemy fleet single-handedly while escorting Arika and Mashiro back to Windbloom. During a battle against a massive Slave, Mai and Arika combine their attacks to defeat it, but Mai is then struck by a shadowy entity, knocking her onto a building roof. This incident results in both Mai and Mashiro vanishing, later revealed to have been relocated unharmed to an island. In the final conflict, Mai battles Kagutsuchi—a creature from the Mai-HiME universe—quelling the threat by removing the sword attached to its head.

Mai wields her signature weapon "Ignition," manifested as four golden rings adorned with magatama, consistent with her earlier powers. Her GEM, the Fire Stirring Ruby, facilitates her materialization as an Otome. Her relationship with Mikoto defines her existence, shaped by their accidental contract and life together in the Black Valley, where Mai provides stability for Mikoto while relying on her for companionship and purpose. Her interactions extend to pivotal mentorship roles for Mashiro and Arika, emphasizing her experience and nurturing nature.