Mashiro Blan de Windbloom is the princess and later the queen of the kingdom of Windbloom in the anime My-Otome. She is a fourteen-year-old girl who turns fifteen during the series, with lilac hair and blue-green eyes. Her personality stands in sharp contrast to her counterpart from My-HiME: rather than being polite, selfless, and reserved, she is boisterous, selfish, and arrogant. This behavior stems from a childhood in which she was thoroughly spoiled, given nearly everything she demanded. As she grew older, doubts about whether she is the true heir to the throne circulated, and these suspicions are later confirmed when the real ruler of Windbloom is discovered. These rumors intensify her feelings of insecurity and inadequacy, causing her already difficult behavior to worsen.

Mashiro often shirks her royal responsibilities, preferring to visit Garderobe to laugh at Arika Yumemiya’s clumsy attempts at Otome training. Her self‑centered actions lead her to raise taxes to fund the rebuilding of her castle and her own birthday celebration, even as the city suffers from rising unemployment. She owns a pet cat named Mikoto and shares a love‑hate relationship with Nagi, leaning strongly toward hatred. Despite her entitled demeanor, she possesses a capacity for change. During a life‑threatening emergency, she forms a contract with Arika that binds their lives together. Initially both strongly oppose the bond, but its life‑binding nature creates a crack in the tension between them, and they slowly grow closer.

Mashiro’s role in the story is that of a monarch struggling with her identity and duties. Her key relationships include her first meeting with Arika and Nina Wáng, whom she encounters while evading palace guards by jumping between rooftops; after she falls, they believe the guards are kidnappers and help her escape. Another significant relationship is with Takumi, the prince of Zipang. When he visits Windbloom in disguise as a civilian, Takumi shows Mashiro the poverty in her own city, shocking her and prompting her to see the realities of her kingdom. Her most notable ability is the formation of a contract that ties her life to her Otome, allowing her to share power and danger. She also temporarily contracts with Nina Wáng through the Neptune Emerald. Over the course of the series, Mashiro develops from a spoiled, irresponsible girl into someone who begins to understand the weight of her position and the importance of those around her.