As the new academic year kicks off at Kitauji High School, Kumiko Ōmae begins her second year filled with excitement and uncertainty within the dynamic atmosphere of the school's concert band. The introduction of fresh faces—first-year students Kanade Hisaishi, Mirei Suzuki, Satsuki Suzuki, and Motomu Tsukinaga—infuses the group with a sense of novelty and energy. Guided by the band's president, Yūko Yoshikawa, Kumiko and fellow band member Tomoe Kabe take on the role of mentors to the newcomers, with aspirations of clinching the coveted gold at the national concert band competition. However, as they embark on this ambitious journey, Kumiko senses a noticeable divide between the seasoned upperclassmen and the enthusiastic new recruits.
A crucial turning point for the band occurs during the Sunrise Festival, where Mirei Suzuki expresses her disillusionment over what she perceives as frivolous behavior among her senior peers. In a moment of camaraderie, Kumiko, along with Kanade Hisaishi, encourages Mirei to rethink her stance, ultimately leading to a brilliant performance by the Kitauji High School Concert Band at the festival.
As practices ramp up, Noboru Taki, the band’s conductor, unveils the piece for the national competition, titled "March Sky Blue Dream," as well as a free selection and an audition on the horizon. Kumiko finds herself balancing the demands of musicianship with her personal life, attending a prefectural festival with her boyfriend Shūichi Tsukamoto while also sharing anxieties about their impending third year of high school with Reina Kōsaka.
The pressure mounts when Tomoe Kabe announces her decision to withdraw from the competition to focus on managing the band. She confides in Kumiko about the struggles she's facing due to inflammation in her temporomandibular joints, prompting her to reevaluate her position within the ensemble. Meanwhile, Kanade shares her frustrations regarding Natsuki Nakagawa, who has been reaching out for assistance despite their considerable age difference.
On the day of the audition, Natsuki's keen observation skills pick up on Kanade's evident lack of enthusiasm. In a heated confrontation, Kanade expresses her reluctance to participate, stating her desire to allow Natsuki to shine as she prepares for graduation. Kumiko steps in, referencing Kanade's past experiences with former senior mentors, guiding her toward resolution. The audition culminates in a victory for Kumiko, Kanade, and Natsuki, their bond fortified through the challenges they faced.
As the Kitauji High School Concert Band undergoes a transformative journey under the guidance of their instructors, Mr. Taki, Satomi Nīyama, and others, they arrive at a pivotal moment. In an unexpected yet mature decision, Kumiko and Shūichi choose to part ways, redirecting their energies towards the band's development. The stakes escalate as the competition heats up, leading to the Kansai band competition where alumni Kaori Nakaseko, Haruka Ogasawara, and Asuka Tanaka return to cheer for their beloved Kitauji High School Concert Band. Despite their determined efforts, they fall short of their national dreams, receiving a disappointing dud gold medal. The sting of defeat lingers as the band's leaders gather to regroup and reassess their strategies. In a heartfelt conclusion, Kanade warmly welcomes Kumiko, who has now stepped into the role of the band's president, signaling an exciting new chapter in her musical odyssey.
