Long ago, Kanata Sorami heard the clear, golden sound of a trumpet being played by a female soldier. In hopes of following in the footsteps of the mysterious musician, Kanata enlists in the Helvetian Republic Army at Clock Tower Fortress.
Kanata meets the other members of her platoon and finds her way around the fortress. After hearing chilling reports of a ghost haunting the old barracks, Kanata and Kureha explore the ruins and find more than they expected.
Rio and Kanata spend the day working on bugle lessons but Kanata falls suddenly ill. With the others gone and no medicine left in the storeroom, Rio must turn to an unlikely place for help.
Kanata struggles to improve her bugle skills when practice doesn't seem to help. Meanwhile, Noel tries to make a replacement lens for the optical sensor.
Kanata, Kureha, and Noel travel to a location in the wilderness that's along the border of No Man's Land to investigate three ancient surveillance devices. The task seems simple enough until the group finds out their hike will be more difficult than they imagined.
It's a bright, sunny day, and Kanata has received her first paycheck! Meanwhile Mishio and the rest of the platoon run into problems when the Mafia comes to Seize.
Second Lieutenant Filicia is usually bright and cheerful but there's a part of her past that haunts her. As summer reaches its hazy peak, memories of her old platoon keep resurfacing, along with visions of their terrible fate.
The rainy season arrives in Seize and a typhoon is on the way. Unfortunately Kureha is preoccupied with Claus, the Desert Wolf hero of the 481st Platoon!
Old Lady Jacott has lived in the mountains for most of her life. She's always been able to take care of herself but now her health is failing, and winter is coming. Rio agrees to help the old woman but soon learns lessons that only Jacott can teach her.
The peace talks between Helvetia and Rome have ended in disagreement and there are rumors of Roman troops on the move. Meanwhile, Kanata and Kureha find a Roman scout lying injured in the snow.
The Demon of Vingt is ready to spark another war and the women of the 1121st Platoon are outnumbered and overwhelmed. Luckily, they use their courage and the sound of the sky for hope.
