Chika Homura,who has lot of interest in playing flute and to participate in Brass Comepetition enters High School.There she meets her childhood friend Haruta Kamijo who is smart and belongs to music club and plays French Horn.Together they encounter a mysterious writing on musical note board written in cipher.
Haruta and Chika wants second year student Miyoko Narushima who plays Oboe, to join their club.But Miyoko has dark past where her puzzle loving brother died of cancer.He left her a Rubik's cube which was left unsolved by Miyoko.
Maren Sei,a Chinese guy adopted by American family has to deal with his issue.He used to play Sax but left it and joined drama club though he didn't know how to act.Both Music Club and Drama Club compete in a drama named Exit Game.
Haruta has to vacant his apartment due to rent problems.With help from his sister and Chika he finds an apartment which is reported to be haunted.How did Haruta solve this problem???
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.
According to the will of Mr. Kusakabe's former teacher, his granddaughter, Makoto, is the only one who knows the whereabouts of the key to his beloved piano. Can they figure out the secret of the key's location?
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.