It's a sweltering day during summer vacation in a remote town in northeast Japan…
The Yamakawa High School brass band clambers aboard a bus, off to provide moral support for their team at a local baseball championship. 13 girls, all of them losers, watch from classroom window. They're stuck in remedial math with Mr. Ozawa (Naoto Takenaka), but their minds are miles away and their ability to focus, . . . .huh? One girl, Tomoko Suzuki (Juri Ueno), stares enviously out the window at the musicians as their bus pulls away. Suddenly, she notices that a caterer's van has pulled up. The driver is beside himself when he realizes that he's missed the bus. As Tomoko watches, an idea takes shape in her otherwise vacant mind…
"Teacher, I'm sure those guys are super hungry. I think we should take them their lunches."
Within minutes, the girls have ditched summer school math and boarded a local train, ostensibly off to deliver the lunches. Heady with their newfound freedom, they sample and then gobble down, one of the lunches, doze off and miss their stop. Before long, they're walking back to the stadium in the sweltering heat, complaining every step of the way. By the time they finally deliver the food, it has spoiled in the heat and the whole band, along with its director Itan (Miho Shiraishi), are rushed to the emergency room with stomach cramps. Only Takuya Nakamura (Yuta Hiraoka) escapes this fate, thanks to the girls who devoured his lunch on the train.
Before long the baseball team is practicing for another game, but the band that normally cheers the team to victory is still out of commission. Takuya Nakamura tries to throw together a new brass band, but his efforts only draw the 13 loser-girls plus 3 other misfits. A brass band needs a lot more than 17 players. Takuya's thoroughly discouraged until he realizes that 17 is the perfect number for a jazz Big Band.
Intense training sessions on school band instruments follow. The girls, who have trouble at first even making a sound, gradually start to play entire melodies and manage to limp their way through "Take the A Train." Gradually, what started as a scheme for cutting class gives way to actual enthusiasm for music.
Everything is hunky-dory, until. . . .
One day before the championship baseball game, the regular band troops into the rehearsal room, fully restored and ready to play. They thank the girls for covering for them and the girls feign relief at not having to perform in public. But on the way home, they burst into tears over their shattered dream. The summer ends on a note of frustration.
When school starts up again in the fall, the girls go back to their usual routines but they can't forget the pleasure and satisfaction they found in music. Still, they're too proud to actually join the regular school band. In an inspired moment, they decide to start their own Big Band, the Swing Girls. Since their former instruments belong to the school band, they'll have to get their own. Brass is pricey and even used horns add up. The first step in getting the band off the ground turns out to be fundraising. The girls try everything, from working part-time jobs at a supermarket, to poaching wild mushrooms in the forest, wreaking havoc wherever they go. Discouraged, some drop out and the Swing Girls dwindle to five, but they finally get their hands on a trumpet, a trombone, drums and a pair of saxes and make a meager start.
Their remedial math teacher turns out to be a jazz enthusiast and he coaches them through the "community noise pollution" stage into some real swing. Excited to see their friends' transformation, others return to the fold, and the Swing Girls finally achieve that Big Band sound. When they hear about a student music competition the girls decide to enter. If their audition video makes the grade, they'll have the chance to play on a real stage. They tape their audition against the spectacular backdrop of snow-capped mountains, but…
If it isn't one thing, it's another. The Swing Girls future hangs in the balance. Will they ever get the break they need. . . ?
