Kotori's mother, formally addressed as Director Minami or the Otonokizaka Chairwoman, is the principal of Otonokizaka High School, the institution central to the events of the story. She is a composed, mature woman with waist-length gray hair and yellow eyes, her appearance often noted for its gentle resemblance to her daughter Kotori. Her background is rooted in the local community: she is a childhood friend of Honoka Kosaka's mother, and the two families have long lived on the same street. She also maintains a longstanding friendship with the mother of Maki Nishikino, a student at the school.

As school director, she takes her responsibilities seriously and genuinely cares about the academy's welfare. However, when faced with the school's impending closure due to declining enrollment, she displays a realistic, almost resigned outlook. She does not believe there is anything she can personally do to reverse the situation, and thus she does not actively campaign to save the school. This pragmatic acceptance contrasts with the fierce determination of the student idol group, yet she never obstructs their efforts. When student council president Eli Ayase requests restrictions on µ's activities after their initial performance fails to draw immediate attention, Director Minami refuses, quietly allowing the girls the space to try.

Her motivations center on supporting her daughter and fulfilling her administrative duties. She is a caring parent who prioritizes Kotori's happiness and autonomy. This is most evident during a pivotal moment when Kotori faces a choice between studying abroad and remaining with her friends. Director Minami accompanies Kotori to the airport and, rather than pressuring her, simply asks if she is sure about her decision, showing a deep respect for her daughter's feelings.

In the larger narrative, she functions as a calm, background authority figure. Her decisions create an environment in which the idols can operate without administrative interference. She attends µ's performances, including the climactic Love Live competition, and witnesses the very outcome she once thought impossible. While she undergoes no dramatic personal transformation, her initial skepticism becomes a quiet acknowledgment of the students' achievement. Her key relationships beyond Kotori include her bond with Honoka's and Maki's mothers, and a professional rapport with the student council. Her notable ability lies in her steady, responsible management of the school's operations even under the shadow of closure, ensuring that student activities can continue until the end.