The year is 2032, seven years after the Second Great Kanto Earthquake decimated Tokyo. Now, the city is reborn as MegaTokyo, built from the labors of mechanical beasts known as Boomers. Originally created to benefit humanity, the mysterious corporation known as Genom now produces Boomers with incredible destructive power as a new type of advanced weaponry, capable of disguising themselves as humans. The AD Police is a new special unit to counter the ever-increasing Boomer-related crimes. Overwhelmed by the sheer amount of crimes and disparity in strength, the AD Police poses little opposition to the Boomers. A mysterious vigilante force known as the Knight Sabers, wearing powersuits more advanced than the military, is the citizens' only hope for protection. Led by Sylia Stingray, Priscilla Priss Asagiri, Nene Romanova, and Linna Yamazaki, these beautiful girls take out any Boomer that steps out of line.

Hajime Shinonome is a 29-year-old seasoned adventurer who has long stepped away from the glory of youthful ambition, instead content with his steady life in Komai Village. During a dungeon expedition, he rescues a young girl named Rirui, who was abandoned and nearly consumed by a slime. Driven by memories of a similarly unforgiving past, Hajime takes her under his care. But as Rirui begins to reveal unexpected abilities while adapting to the rhythm of village life, Hajime finds that their shared existence may prove to be more consequential than any other quest he has ever attempted.

Orphan Himari Momochi's only link to her late parents is the house they secretly bequeathed her, which she does not learn of until her 16th birthday. Thrilled by the opportunity to know more about her family, Himari arrives at the rumored haunted house and is bewildered to find three young men already living there: Aoi Nanamori, who identifies himself as the guardian of the place, and his two familiars, Yukari and Ise. Although they allow her to stay overnight, they warn her to leave the next day so she can avoid harm from ayakashi—wandering spirits that sometimes attack human beings. Surprisingly, Himari is unaffected by her spectral encounters and determined to move in to the residence. After she discovers that Aoi had become guardian unwittingly and is now confined to the property, forgotten by the outside world, her resolve only grows stronger. Touched by his story, Himari decides to find a way to free Aoi from his dim fate, and she convinces the three Momochi House protectors to accept her as their landlady. However, the mysterious Kasha who keeps sending hostile ayakashi to Himari's new home seems to have darker plans for Aoi's future.

Hibiki Tachibana has defeated many powerful enemies, saved countless innocent lives, and escaped from numerous desperate situations, but she is currently finding herself unable to escape from her most desperate situation yet—summer homework! Although her high school life is relatively unremarkable, her career as a member of the military organization S.O.N.G. is anything but. Using powerful, ancient armor known as Symphogear, Hibiki and her teammates work with the United Nations to deal with international disputes and disasters. During a mission briefing at headquarters, Hibiki is made aware of a mysterious organization known as the Bavarian Illuminati, who has been responsible for several major disasters in the past and currently operate in the war-torn country Val Verde. Together, Hibiki and her team infiltrate one of the Bavarian Illuminati's manufacturing plants and free hundreds of slaves. Exposed, alchemists Saint-Germain, Cagliostro, and Prelati reveal themselves as the organization's top brass, and—using alchemical powers—declare a global revolution while sacrificing thousands of lives. Faced with yet another threat to the world's survival, Hibiki and her allies must confront the Bavarian Illuminati in their most difficult and destructive battle yet.