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.
Au début de l'été, Kanata et Noël ont la joie de recevoir chacune une lettre. Parmi le courrier reçu se trouvent également les nouvelles directives du quartier général pour Filicia. Cette dernière décide d'organiser une excursion en montagne avec les trois plus jeunes recrues de l'unité.
初夏、クラウスの手で時告げ砦に届けられた何通かの手紙。
手紙の差出人を見て喜ぶカナタと、嬉しそうなノエル。
忌々しげに悪態を吐くリオと、そんな皆を少し寂しそうに眺めるクレハ。
第1121小隊の隊員達は、それぞれに違った反応を見せます。
そしてフィリシアの元に届いた一通の手紙。
そう、その手紙がカナタ達の運命を左右する、すべての始まりだったのです――！
