Kumiko Ōmae has wavy auburn hair that falls to her shoulders and striking amber eyes. She is often seen wearing the Kitauji High School uniform, which she dons in both the winter and summer styles. During concerts, Kumiko also wears a variety of the band’s performance attire, highlighting her role as a dedicated member of the ensemble.

At the start of the series, Kumiko Ōmae is an introspective and somewhat indecisive young girl, often questioning her own motivations and capabilities. This self-doubt leads her to be contemplative, frequently reflecting on the deeper meaning behind her choices and actions.

Despite her uncertainties, Kumiko is inherently kind-hearted and empathetic, always showing concern for her friends and fellow bandmates. She can be socially awkward at times, struggling to express her true feelings or address conflicts directly.

As the series unfolds, Kumiko’s determination and dedication to the concert band intensify. Her passion for music grows, and she becomes increasingly confident in her abilities, fueled by a newfound sense of purpose. A key influence in her development is her evolving relationship with Reina Kousaka, whose presence challenges Kumiko to push her boundaries and strive for greater excellence.

Kumiko Ōmae is the daughter of Kentarou and Akiko Ōmae and the younger sister of Mamiko Ōmae. Inspired by her older sister, Kumiko developed a passion for the euphonium and became an accomplished player from a young age. She was a member of the Daikichiyama Middle School Band, which earned a gold award at the prefectural (first-round) tournaments. However, the band fell short of qualifying for the national competition, an event that led to a strained relationship between Kumiko and Reina Kousaka.

On her first day at Kitauji High School, Kumiko Ōmae comments on the poor state of the school’s concert band while making new friends, including Hazuki Katou and Sapphire Kawashima. Sapphire shares her background in music and interest in joining the band, but Kumiko is initially hesitant, particularly due to her complicated past with Reina Kousaka. After much contemplation and seeing Hazuki and Sapphire’s enthusiasm, Kumiko decides to join the band, but only after resolving her issues with Reina.

Kumiko had initially considered trying a different instrument in high school, even avoiding the bass section. However, she eventually returns to the euphonium after being encouraged by Asuka Tanaka and Aoi Saitou, who reveals Kumiko’s musical background.

The band begins preparations for their performance at the SunFes festival, and their hard work pays off, earning a positive reception from the audience. Kumiko later decides to spend time with Reina instead of Shuuichi Tsukamoto, further strengthening their bond.

Kumiko successfully passes an audition to perform in the upcoming competition, growing closer to Reina, who confesses her love for Noboru Taki. Though Kumiko struggles with learning the piece, Taki’s encouragement helps her overcome the challenge. By the end of her first year, Kumiko’s school band wins the Kansai regional competition.

As the second year progresses, Kumiko’s band prepares for the national competition, winning gold at the Kansai regionals and earning their spot at nationals. Kumiko also helps resolve conflicts, such as Nozomi Kasaki’s return to the band and Mizore Yoroizuka’s issues. Despite Reina’s frustrations about Taki, Kumiko grows increasingly reflective about her relationships with others, especially Reina.

In her second year, Kumiko becomes more involved in band leadership, particularly as the band navigates complicated emotions and personal struggles. She helps her friends reconcile with their pasts, including Asuka Tanaka, whose tumultuous family history comes to light. Asuka’s decision to stay in the band and support her teammates is a turning point for Kumiko, who also reconciles with her sister Mamiko after years of jealousy.

The third year sees more personal challenges. Kumiko deals with the complex emotions surrounding Taki’s wife and the band’s growth, while her bond with Reina deepens. The national competition approaches, and Kumiko and her bandmates prepare for their final performance. Although Kitauji wins bronze at nationals, Kumiko’s emotional reunion with Mamiko marks the culmination of her high school journey.

After graduation, Kumiko transitions into a leadership role, becoming the new president of the concert band alongside Reina and Shuuichi. As she guides the new generation of musicians, Kumiko reflects on her journey, from a hesitant, introspective first-year to a confident and capable leader.

In the epilogue, Kumiko is seen working as a teaching assistant at Kitauji High School, continuing her connection with the concert band as an advisor, embodying the spirit of growth and mentorship that defined her high school years.

Family

Mamiko Oumae
Kumiko’s older sister. They have a close relationship, though they often tease and argue. Mamiko is Kumiko’s inspiration for joining the band, and despite their differences, they share a deep bond.

Akiko Oumae
Kumiko’s mother. Little is revealed about their relationship in the series, and Akiko’s role is more in the background, though she seems to have a cordial relationship with Kumiko.

Kentarou Oumae
Kumiko’s father. Similar to Akiko, Kentarou’s relationship with Kumiko is not extensively explored, but he plays a supportive role in her life.

Kitauji High School Students

Reina Kousaka
Kumiko’s relationship with Reina is complex, initially marked by tension due to a misunderstanding in junior high. After resolving their issues, they grow very close, forming a strong bond based on trust and mutual support. Reina becomes someone Kumiko is deeply connected to, often showing a more emotional side of herself that she doesn’t reveal to others.

Asuka Tanaka
Asuka is Kumiko’s section leader and mentor. She first ropes Kumiko into the euphonium section and later becomes a close friend. Asuka’s care for Kumiko deepens as she shares personal stories with her, and they form a strong, supportive bond that lasts throughout their time in the band.

Shuuichi Tsukamoto
Shuuichi is Kumiko’s childhood friend with whom she has a somewhat awkward and complicated relationship. After a brief falling out in junior high, they become friends again in high school. Shuuichi harbors romantic feelings for Kumiko, which causes some tension between them. Despite their growing distance, their bond remains strong, and they continue to support each other musically. Kumiko eventually acknowledges her feelings for him in the light novel continuation, though their romantic relationship is not explored in the anime.

Hazuki Katou
Hazuki is one of Kumiko’s first friends at Kitauji High. They get along well, and Kumiko supports Hazuki’s feelings for Shuuichi. Kumiko cares for Hazuki and even sacrifices her own opportunity to attend the festival with Shuuichi to allow Hazuki to go instead, showcasing their close friendship.

Sapphire Kawashima
Sapphire is another close friend of Kumiko’s, and along with Hazuki, they form a trio of friends who are often seen together. Their bond is strong, and they support each other throughout the series.

Natsuki Nakagawa
Natsuki and Kumiko share a mutual respect for each other as fellow euphonium players. However, Natsuki initially feels envious of Kumiko’s skills. Over time, they become closer after an open conversation where they address the tension, and Natsuki begins to appreciate Kumiko’s talent.

Kitauji High School Teachers

Noboru Taki
Taki is Kumiko’s band director, initially coming across as strict and demanding. However, Kumiko comes to respect him as she realizes that his strictness stems from a genuine desire to help the band succeed. Taki becomes an important figure in Kumiko’s development, offering support and encouragement when needed.

Michie Matsumoto
Michie is a strict but respected teacher at Kitauji High. Though Kumiko finds her strict, she has a respectful and cordial relationship with her. Michie also shares a connection with Kumiko’s family, particularly her mother.

Masahiro Hashimoto
Hashimoto is friendly toward Kumiko, though he does not teach her directly. He engages in a conversation with Kumiko about Taki’s past, revealing personal details that deepen her understanding of him.

Other

Azusa Sasaki
Azusa and Kumiko were friends in junior high, and they reconnect during their time in the Kitauji High School band, especially during the SunFes festival. While not deeply explored in the anime, their friendship serves as a reminder of Kumiko’s connections from her earlier years.