Сістіна Фібель

Sistine admires magic greatly and wishes to discover the secret of the Flying Castle, which no one knows. She maintains a strict, no-nonsense demeanor throughout, and often scolds Glenn for his lackadaisical attitude. She initially hates Glenn, believing him to be as incompetent as he looked due to his lack of enthusiasm. When he actually starts doing his job, however, she begrudgingly begins to respect Glenn as a highly effective teacher. Her personality and appearance resembles Sara Silvers, whom Glenn was very close to.

As the series progresses, it seems as though Sistine has developed feelings for Glenn, but is too shy to speak of them. She is called "Sisti" by Rumia, and "White Cat" by Glenn.