Spring in the first year of high school. Kumiko, a member of the brass band in junior high school, visits the high school brass band club with classmates Hazuki and Sapphire. There, she comes across Reina, her former classmate from junior high. Hazuki and Sapphire decide to join the club, but Kumiko can't make up her mind. She recollects her experience with Reina at a competition in junior high school.