Freshman high school student and Western concert flute novice Chika Homura wants to reopen her high school's Brass Club, which abruptly closed a year before. However, the principal refuses to give permit unless she manages to gather nine members in three weeks time. Although she is helped by her childhood friend, Haruta Kamijo, who plays the French horn, none of the ex-members seem interested to accept her invitation. Nevertheless, when Chika shows determination while convincing junior Kyoji Miyamoto, a sulky alto saxophone player, to join, members begin to trickle into the club: seniors and couple Seiji Katagiri and Wakaba Noguchi, who play trumpet and oboe, are the first to join, followed by freshmen Megumi Nagatsuka and Taeko Yonezawa, who play trombone and tuba, respectively. Kyoji also decides to sign up after some hesitation.