5 years have passed since the Alliance War of Independence, also know as the First Space War...

Awoken from his confines, Elais finds himself in a seemingly abandoned space station. While roaming its empty hallways, he's greeted by a familiar humming, which guides him to a dimly lit hangar, where he encounters a giant mech, in front of which stands a mysterious girl, welcoming him. This is where the story begins.

[Edited from the official website]