Superb Song of the Valkyries: Symphogear.

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.