In the fifth installment of Senki Zesshou Symphogear, humanity faces a dire threat from the Custodians, an ancient race blamed for the diversity of languages. Hibiki Tachibana and her fellow Symphogear warriors embark on a mission to Antarctica to recover a powerful artifact. Amidst clashes with the sinister Noble Red, remnants of a notorious organization, the race is on to prevent their schemes and protect the relic from falling into the wrong hands. Can the Symphogear wielders and S.O.N.G. thwart the dark forces plotting against them?