The menace of the Custodians—the ancient, intelligent species blamed for condemning humans to speak separate languages thousands of years ago—has finally arrived. Hibiki Tachibana, Tsubasa Kazanari, Chris Yukine, Maria Cadenzavna Eve, Kirika Akatsuki, and Shirabe Tsukuyomi, the Symphogear wielders, are dispatched to the Antarctic to rescue an ancient artifact. Due to international accords, the artifact is transferred to American researchers when it has been secured and the scientific crew present has been rescued from a Coffin, the automatic security device guarding it.