High school brass band club members and newly reunited childhood neighbors Haruta and Chika decode a mysterious message hidden in the music of Bach and become rivals in love.

The band club is growing. In order to get a budget increase, Chika and Haruta agree to track down one of the student council's problem club leaders. Why is the geology club leader on the run? What is her connection to a mysterious radio station?

Naoko volunteers to help Chika rehearse for the upcoming qualifying round, but wants her help in return. Her aunt has returned to Japan in search of information on her first love and goes to the school's First Love Sommelier for assistance.

Mr. Kusakabe has collapsed from exhuastion! To help out Mr. Kusakabe, Chika and Haruta investigate the mystery behind the Fujigasaki High School brass band club advisor's suspension and the peeping Tom known as Asmodeus.

The day of the district contest has arrived! When Haruta goes missing, Chika goes to look for him and runs into a writer who's interested in Mr. Kusakabe's past. Can the mystery of a lost dog's true owner appease the writer's curiosity instead?

Mr. Kusakabe got an offer to conduct for the Hamamatsu Orchestra. Will he leave the Shimizu South High School Brass Band Club? Why did he skip on the performance as a conductor years before? Haruta and Chika follow him to find out.