TV-Series
Description
Aoi Saitō is a student at Kitauji High School who is two years ahead of the protagonist, Kumiko Oumae. She is a third-year student and a member of the school's concert band, where she plays the tenor saxophone. She is a childhood friend of both Kumiko Oumae and Shuuichi Tsukamoto, having grown up with them in the same neighborhood, though they grew apart over time before being reunited in high school.

Physically, Aoi is described as a slim teenage girl of below-average height, standing at 155 centimeters, with long black hair that she often styles into two braids. She has a calm and mature presence. Her personality is characterized by honesty, discipline, and a serious, hardworking nature. She is generally friendly and reliable, often appearing calm and collected in most situations. Aoi is a dedicated student who consistently earns high grades and takes her academic responsibilities very seriously.

However, beneath this composed exterior, Aoi harbors deep-seated insecurities and a tendency to hide her true feelings. She feels immense pressure to succeed through constant effort, a trait she has possessed since elementary school. This leads to feelings of inadequacy, especially when comparing herself to her classmate, Asuka Tanaka, whom she views as a true genius who effortlessly excels at both music and academics. While she admires Asuka, this admiration is tinged with envy and a sense of inferiority, as Aoi sees herself as someone who must work tirelessly to achieve results. Her inner conflict is a major part of her character, making her a realistic portrayal of a student struggling with self-doubt and past regrets.

Aoi's primary role in the story centers on her difficult decision to leave the concert band. As a third-year student, she struggles to balance the band's increasingly rigorous practice schedule, under the strict new guidance of conductor Noboru Taki, with her attendance at a preparatory school for university entrance exams. Feeling she has reached her limit, she publicly announces her departure from the club just before the audition for the regional competition. While she officially cites the need to focus on her studies, the real reason for her withdrawal is more complex and emotionally driven. She is haunted by guilt over an incident in the previous year, when a group of unmotivated third-year students drove away many talented first-years, including Nozomi Kasaki. Aoi, who tried to mediate without taking a side, was unable to prevent the mass exodus and feels she failed to stand up for what was right. She cannot fully enjoy the band's newfound success and pursuit of national competition because she has not yet made peace with her own past inaction.

Aoi's most significant relationships are with her childhood friend Kumiko and her classmate Asuka. With Kumiko, she shares a comfortable and trusting bond, often giving her advice. Despite the age difference, they can speak openly, with Kumiko sometimes using the informal name "Aoi" in private. Her relationship with Asuka is more complex. As classmates, they are close enough to call each other by their first names, but Aoi is constantly aware of the gap in their natural talents. Later, when Asuka faces her own personal problems, Aoi feels a sense of relief, realizing that even a genius like Asuka is human and has struggles, which ultimately strengthens their friendship as equals. She also has a supportive relationship with Haruka Ogasawara, her section leader, to whom she turns when making her difficult decision to quit.

Aoi undergoes significant development, primarily through her departure from the band. While this act is born from regret and a sense of personal failure, it also shows her honesty with herself. She chooses to step away rather than pretend her guilt does not exist. After graduating from Kitauji High School, she goes on to attend a local private university's literature department. There, she is invited to visit the university's concert band club, where she rediscovers her passion for music. She decides to join, reuniting with her former senior, Haruka, and the two of them eventually return to cheer for their old high school band at a competition, showing that she has found a way to reconcile with her past and continue playing.

In terms of abilities, Aoi is a skilled musician, playing a professional-grade YAMAHA YTS-82Z tenor saxophone. She is also a dedicated and successful student, consistently placing within the top ten in national mock exams. Outside of music and academics, she enjoys drawing, particularly portraits, though she is modest about her skill level. She also has a keen interest in literature, counting authors like Natsume Sōseki and Mori Ōgai among her favorites.