Miyuki is a young lady who is pretty, smart, and well-mannered,who also went to an all girl school before coming to ryoo high school, and comes from a wealthy family. Her mother acts like a younger sister to Miyuki. She always uses extremely polite Japanese, even when talking with her closest friends. She was the class president for her grade level in her first year, at the same time that she became good friends with Kagami Hiiragi. During her second year of high school, Miyuki was put in the same class as Konata Izumi and Tsukasa Hiiragi. Miyuki's classmates often rely on her for help with their studies, and she is often shown giving impromptu but highly-detailed, encyclopedic definitions or explanations on diverse and obscure matters. Starting from the episode I Can't Suddenly Change, Miyuki and her friends enter their final year in high school, she placed in Ms. Kuroi's class again. In To Be Decided, Miyuki and the rest of the main cast take place in cheer leading session for the school's cultural festival.
Role in Subspace Emmisary