During a concert by idol group Zwei Wing, an alien force known as the Noise attack the stage. Group members Tsubasa Kazanari and Kanade Amou suppress the attack using their Symphogear armor, but despite their best efforts, innocent bystander Hibiki Tachibana is fatally injured. Distraught and much to Tsubasa's dismay, Kanade sacrifices herself in the process to save Hibiki.
Two years later, Hibiki lives on. Tsubasa now fights alone. With the threat of the Noise increasing, Hibiki finds herself encountering the Noise once again but this time she is granted a chance to become attuned with the same Symphogear that Kanade wielded.
A sarcophagus rises from the depths of a lake during a snowy midsummer. A relic of the precursor civilization, and one containing the most revered of the dead: the remains of an Anunnaki. While S.O.N.G. may have hoped for answers, the recovery of the body only signals the start of a new battle. Monsters, gods, and curses surround Hibiki and her friends, and some of those new threats look far too familiar for comfort. While struggling with doubt, pain, and loss, can the girls let courage bloom, even so? Or will the loneliness that comes from humanity’s discord overwhelm them?