A young girl named Kanata Sorami joins the army with the hope of learning to become a good bugler. She is assigned to a place called Seize, which is currently holding a festival where people splash each other with water. She is found by her superior, Rio Kazumiya, who gives her a bath and tells her about the legend of the Fire Maiden. While looking at a bell owned by Rio’s father, an owl steals it, forcing Rio to stop Kanata falling off the balcony trying to get it. As Rio participates in the festival, Kanata decides to search for the bell. She finds it hanging off a ledge, but when she goes to get it she falls into the lake, where she sees the golden skeleton of a winged creature. Stranded at the bottom of a canyon, she plays her bugle where she is responded to by Rio on her trumpet. She takes her to the Time Telling Fortress and plays the trumpet as the sun rises, introducing herself as Kanata’s bugling teacher.

The squad take a "field trip" to the mountains where some observers need a maintenance check. Kanata, Kureha and Noël are forced to carry heavy backpacks on their hike up. Whilst they find the first observer quickly, the next one lies at the top of a mountain. They take a break at a running river but soon return to find their backsacks ravaged of their food and their compass. Despite the hunger, they eventually manage to find the remaining observers. At the last observer, Filicia shows the others signatures left by former members who had observed No Man’s Land from that point. They are then taken to a hot spring where Rio, who had fought against a boar to get some berries, awaits.