カージ合衆国とヴィルカール帝国という大国の
緩衝地帯に設定されたフロスト中立特区。
観光地として成功を収めている反面、様々な種族が移住してきたことから事件や衝突が絶えない場所でもあった。
その中立特区に事務所を構えるトリガー探偵事務所の調査員として働く主人公・榊カイ（さかき かい）。
彼の目的は先の大戦で行方不明となった幼馴染・楪紗衣奈（ゆずりは さいな）の行方を捜すこと――
この地で紗衣奈の目撃情報はいくつかあるものの、
その足取りは掴めない状態が続いていた。
――そんな中、街を見下ろす高台で空に手を伸ばすミリィという少女と出会う。
かつての紗衣奈と同じく、争いが絶えない世界を憂い、平和を望むミリィ。
この出会いが、カイの、中立特区の、そして世界の運命を大きく変えていく。
失くした過去を乗り越え、未来へと歩む物語――ここに開幕。
The great powers of the United States of Kage and the Vilcar Empire
Frost Neutral Special Zone set as a buffer zone.
While it has been successful as a tourist destination, it has also been a place of constant incidents and conflicts due to the immigration of various tribes.
The main character, Kai Sakaki, works as an investigator for the Trigger Detective Agency, which has an office in the neutral special zone.
His purpose is to search for his childhood friend Eina Yuzuri, who went missing during the last war.
Although there are several sightings of Saina in this area,
It continued to be difficult to keep track of her steps.
- Meanwhile, she meets a girl named Milly who is reaching for the sky on a hill overlooking the city.
Just like Saina before her, Milly is worried about a world filled with constant conflict and desires peace.
This encounter greatly changes the fate of Kai, the Neutral Special Zone, and the world.
The story of overcoming a lost past and walking toward the future begins here.
