A new year signifies a new beginning, and that seems to be the case for Kitauji High School’s concert band. Following the graduation of the third-year seniors comes the entrance of the first-year juniors. The band members put in their utmost effort in practicing for their goal—to enter nationals. The now second-year Kumiko Oumae, along with her friends, is met with the new and quirky batch of first-years, resulting in friction and conflict between the band members. However, as time passes, their inner feelings slowly unravel, but not every conflict is as easy to solve as the other. The trust and bonds between the band members will be challenged as they push forward for their regionals.

After swearing off music due to an incident at the middle school regional concert band competition, euphonist Kumiko Oumae enters high school hoping for a fresh start. As fate would have it, she ends up being surrounded by people with an interest in the high school brass band. Kumiko finds the motivation she needs to make music once more with the help of her bandmates, some of whom are new like novice tubist Hazuki Katou; veteran contrabassist Sapphire Kawashima; and band vice president and fellow euphonist Asuka Tanaka. Others are old friends, like Kumiko's childhood friend and hornist-turned-trombonist Shuuichi Tsukamoto, and trumpeter and bandmate from middle school, Reina Kousaka. However, in the band itself, chaos reigns supreme. Despite their intention to qualify for the national band competition, as they currently are, just competing in the local festival will be a challenge—unless the new band advisor Noboru Taki does something about it.

Following their success in the qualifying round for the Kansai regional competition, the members of the Kitauji High School concert band set their sights on the next upcoming performance. Utilizing their summer break to the utmost, the band participates in a camp where they are instructed by their band advisor Noboru Taki and his friends who make their living as professional musicians. Kumiko Oumae and her friends remain determined to attain gold at the Kansai competition, but trouble arises when a student who once quit the band shows interest in rejoining and sparks unpleasant memories for the second-year members. Kumiko also learns about her teacher's surprising past and the motivation behind his desire to lead the band to victory. Reaching nationals will require hard work, and the adamant conviction in each student's commitment to the band will be put to the test.

Haruka Nanase and Makoto Tachibana have started middle school and must adjust to the changes that come along with growing up. While Makoto fits in with his classmates and remains positive about swimming, Haruka struggles to befriend others or join his school's swim club, as his previous issues with swimming trouble him. Distancing himself from his lively classmates and the swimming club, he has difficulty deciding which club to join instead. The rest of his classmates, including Makoto, are also hesitant as to which clubs to participate in. After an argument leads them to join the swimming club anyway, the boys strive to hone their skills, harmonize their swimming styles, and refine their conflicting feelings toward swimming and each other. As determination and talent run high, Haruka and Makoto—along with their classmates—discover themselves and improve their talents during their starting days.