In Mai-Otome, Miss Maria, as everyone calls her, is one of the teachers at Garderobe Academy, along with Yukariko Steinberg. She is also a member of the Garderobe administration, reporting to headmistress Natsuki Kruger.
Maria is a representative of an older generation of Otome. The loss of former schoolmates, sent as Meisters to the War of the Dragon Lord 50 years ago, left her disillusioned about the true purpose of the Otome system. She holds that those students who are unable to accept the fate of possibly fighting their friends must quit Garderobe immediately. This is proven in Episode 8 of My Otome, when Arika and friends break into the underground chamber in the building that serves as Fumi's tomb. Maria shows up and reveals to the girls that she once served as a Coral student, and was the little sister to one of the Otomes of the old order, Monica, the Flowing Diopside of Water. Maria also demonstrates great respect to traditions and customs, and is annoyed whenever Natsuki disregards them in favor of her own political agenda.
After the Artai invasion of Windbloom and Garderobe, Maria retains her position as a teacher, but holds nothing but contempt for the new administration, including Nagi Dài Artai and his newly-contracted Otome Nina Wáng, whom she considers unworthy of being a Meister with so much yet to learn.
In the final episode, she is seen using her Robe for the only time in the TV series, during the combined Otome assault on Fuka Castle. To the sheer surprise of other Otome present, Maria appears much younger than without her Robe, makes a comment about Natsuki's perceived lack of grace, and then demonstrates superhuman speed and agility in her fight with a Slave.
Miss Maria's GEM is known as the Eternal Recurrence Jasper (久遠の碧玉 Kuon no Hekigyoku?). As a member of Garderobe staff, she does not require an explicit certification to unlock her Otome powers, but their availability depends on the status of the Fumi System. Her Element is a rapier.
She is the only on-screen character to demonstrate the change of biological age with materialization. When using her Robe, Maria looks significantly younger than she actually is, similar in appearance to the young version of her seen in My-Otome 0. It is unknown whether this ability is unique to Maria, or common among elderly Otome, as she is the only Otome of advanced age to be seen thus far.
In Mai-Otome Zwei, Miss Maria becomes the third character to be petrified by Yuna, after Miyu and Shizuru Viola. In episode 1, the Unknown Entity, after infiltrating the Fumi System chamber, defeats Maria soon after she enters it. She is revived in episode 4, along with the other petrified victims.
Miss Maria appears briefly in the teaser-trailer for the prequel Mai-Otome 0~S.ifr~. There, she is younger than in My-Otome proper, similar in appearance to her Robe-wearing form. She has a Meister GEM and seems to be an aide of Una Shamrock, the Headmistress of Garderobe at the time of My Otome 0. She also appears for a few seconds in the first episode of My-Otome 0~S.ifr~, overseeing the Pearls' performance class (in somewhat the same capacity as Yukariko Steinberg does for the Corals in the original series), which means she is the homeroom teacher for the Pearl Class. On Episode 2, she makes comments to Una Shamrock about sending the Five Columns and the task force to deal with Schwartz, and seriously reminds Una about the main purpose of Garderobe: Maintaining peace and order without too much interference by force. After the defeat of the Columns, she announces that she will take the place of Una Shamrock as headmistress of Garderobe, and that the other Columns (except Elliot) had their Otome licenses provoked for a month.