A sequel to Gunparade March. About fifty years ago, an alien race, known as the "Phantom Beasts," appeared on Earth and began to kill all humans. A student draft was declared, and high school students were recruited to become mecha pilots to fight these aliens. Gunparade Orchestra features the teenage mecha pilot soldiers of the 108th Guard Squad, a weak unit stationed in Aomori. Ishida Sara has arrived to be their new company commander, and she's determined to get their team in shape! If she can handle the frigid Aomori weather and the resistance of the 108th squad pilots, maybe they can survive the ongoing war against the Phantom Beasts...

(Source: MangaHelpers)