The Frost Neutral Territory - a buffer zone between the superpowers of the Karg Federation and the Vilcar Empire. A tourist hotspot, yet a melting pot of constant conflict with its diverse immigrant populations.

Sakaki Kai, the protagonist, is an investigator at the Trigger Detective Agency based on this neutral ground. His mission? To track down his childhood friend Yuzuriha Saina, who vanished during the last great war.

While there have been scattered sightings of Saina in this area, her trail has gone cold.

Then, from a hilltop overlooking the city, Kai crosses paths with Millie - a young girl reaching up towards the sky. Much like Saina from years past, Millie laments the endless cycle of violence and yearns for peace. This meeting isn't just a big deal for Kai or the neutral district—it will shake things up for the whole world.

A tale of confronting lost pasts to stride towards a new future - the curtain rises here.

[Translated and edited from the official website]