The deadly confrontation with the Devil King, Oda Nobunaga is over, but the struggle for supremacy continues in Warring Countries-era Japan, as the armies of Takeda Shingen and Uesugi Kenshin repeatedly engage battle at Kawanakajima. Meanwhile, on the easternmost side of the battlefield, two outstanding characters bound by destiny—one clad in azure and the other in crimson—are about to clash in a long-awaited, decisive duel. Then a sudden dispatch informs that a huge army has surrounded the forces of Takeda, Uesugi and Date at Kakanakajima. Their leader is Toyotomi Hideyoshi, the man who inherited Nobunaga's dreams and ambitions, and who is now going to bring havoc over Japan once again! (Source: Production I.G)

Following the events of Senki Zesshou Symphogear G, Hibiki Tachibana, Tsubasa Kazanari, and Chris Yukine continue to operate under the command of Genjuurou Kazanari. Meanwhile, Maria Cadenzavna Eve, Kirika Akatsuki, and Shirabe Tsukuyomi are taken into protective custody. With peace restored, everyone returns to their daily lives; however, the appearance of the alchemist Carol Malus Dienheim and her subordinates—the Autoscorers—threatens to draw everyone back into a conflict. Armed with a strange and magical power, Carol wishes to initiate the apocalypse and bring destruction to the world... and she is willing to sacrifice everything to do so. Against this mysterious new foe, the six Symphogear wielders must rise to the challenge in order to protect what they hold dear. However, will Carol and her Autoscorers prove to be too much to handle in this fight to protect the fate of the world?

Three months after a Lunar Attack which nearly caused Earth's destruction, Hibiki Tachibana, Tsubasa Kazanari, and Chris Yukine continue to fight the Noise—a mysterious alien threat—using powerful armor known as Symphogear. After defending an American convoy from a Noise attack, Hibiki and Chris race toward the Queens of Music concert hall to attend one of Tsubasa's concerts. Meanwhile, Tsubasa and rising international superstar Maria Cadenzavna Eve deliver an amazing performance that is broadcast throughout the entire world. Just as the concert is about to conclude, a group of Noise suddenly appear, plunging the hall into chaos. Amidst the panic, Maria declares war against the world as the successor of Finé—Chris' former mistress—and her allies Kirika Akatsuki and Shirabe Tsukuyomi reveal Symphogear powers of their own. After initiating a skirmish with Tsubasa and her teammates, they retreat mysteriously, leaving the three friends bewildered as to what their true intentions could be.

After a blinding light emanates from her phone, soft-spoken Yuzuki is suddenly transported to an alternate world known as Shinga. The strange place resembles the Sengoku period—a turbulent time in Japanese history known for long civil wars that ravaged the country. Here, the Gekkazoku, tribes of non-human creatures like vampires and werewolves, live in harmony with humans. This harmony was maintained under the governance of Himemiko, a woman with the power to protect Shinga. However, due to her mysterious disappearance, the world has fallen into disarray. Now, Yuzuki must find Himemiko in order to go back home; but, the ongoing feud between the warlords only impedes her progress.