AllMovie

A group of scheming Japanese schoolgirls attempt to get out of summer math class by delivering bento boxes to the school's brass band, in the process contaminating the meals and forming a stand-in band with the one real musician who hasn't fallen ill. A group of struggling female math students are in class when daydreaming Tomoko (Juri Ueno) peers out the window and sees the brass band loading into a bus to perform at a local baseball game. Shortly after their bus pulls away, a catering truck carrying the band's bento boxes arrives to discover that the band has left without their meals. Tomoko immediately recognizes this as a surefire way to get out of class for the day, and proposes to the teacher that the girls deliver the lunches personally. But on the way to the game the girls drop the lunches into a mud puddle, and decide to dunk them in a local stream to clean them off. In the process, the bento boxes get contaminated, causing everyone in the band except for Nakamura (Yuta Hiraoka) to fall badly ill. The only thing that saved Nakamura was the fact that Tomoko ate his lunch before the girls arrived. Now, as the rest of the band gets rushed to the hospital, it's up to Nakamura to find some replacements. Naturally, he recruits the girls who caused all the trouble in the first place. Over the course of the next few days, the girls really begin to enjoy playing music. When the band recovers and comes back to claim their instruments, however, the girls scheme with Nakamura to raise enough money top purchase their own instruments, ultimately forming the band "Swing Girls and a Boy" and rehearsing for their debut performance at the upcoming winter music festival.