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.
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.
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.
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.