The year is A.D. 2089, and it has been eight decades since Space War I irrevocably altered the fates of both the human and Zentraedi communities. Following an extended period of peace on Earth, a previously unknown alien civilization known as the "Marduk" suddenly make their presence known within the Solar System. As UN Spacy clashes with the Marduk military, a chance encounter with Hibiki Kanzaki, a fledgling reporter for SNN, leads to the discovery of Ishtar, an "Emulator" who strengthens the Marduk's fighting prowess through song. Determined to impart wisdom and culture upon Ishtar, Hibiki escorts her to Earth, where they team up with expert Valkyrie pilot Silvie Gena to stave off certain doom orchestrated by Marduk's commander, Ingues, and prevent the utter annihilation of their planet.