In the kingdom of Rimgarde, two mysterious giant robots begin a duel that erases nearly all human life before they disappear. Twelve years later, the young empress of Enastoria, Yuinshiel Asteria, works tirelessly to maintain both her authority and the support of her citizens. But the peace of Enastoria is threatened when survivors of Rimgarde arrive. Armed with giant robots called Regalia Gear, they look for Yuinshiel's adopted sister, Rena. The latter is forced to reveal herself as not just a Regalia Gear wielder, but a real Regalia—a human capable of transforming into a giant robot—and the culprit behind the fall of Rimgarde. Suddenly caught up in an international dispute, Yuinshiel must preserve the security of her country while also protecting Rena from those who wish to abuse her powers. However, by fighting for her sister, Yuinshiel risks triggering the same calamity that once destroyed Rimgarde. Amid such a precarious situation, the two girls push their bond to its limits as they fight not only for themselves but for the world's safety as well.

Above Earth, invisible to humans, float the Heavens—a collection of floating island kingdoms supported by the magic of their godlike inhabitants. The mysterious power source known as Akuto enables this magic to exist, but this is quickly running out. In response to this energy crisis, most of the kingdoms in the Heavens agree to use the minimum amount of Akuto required to sustain themselves, except for the Magical Kingdom. The leader of this kingdom, the Magical King Munto, believes that Akuto can be replenished if he travels to Earth and meets a mysterious girl shown to him by a seer. While Munto sets off on the dangerous journey, the other kingdoms attempt to destroy the Magical Kingdom and acquire the remaining Akuto for themselves. On Earth, Yumemi Hidaka is dealing with her own problems. She can see floating islands in the sky that nobody else can. While her best friend Ichiko Ono believes her, Yumemi wonders if she is going insane. When Munto suddenly appears before her, Yumemi dismisses him as a mere delusion. She is more concerned about her 13-year-old friend Suzume Imamura, who is attempting to elope with her delinquent boyfriend. As the Magical Kingdom nears the point where it will fall from the sky, Munto's quest to save both the Heavens and Earth grows increasingly desperate.

Mitsugu Banba is a high school girl who finds meaning in donating blood. She frequently visits a blood bank to donate blood, despite being harshly treated by the nurse. One day, she encounters a beautiful girl who looks like she's from overseas at the blood bank. The pale girl looks like she's about to faint any minute, but then, she starts destroying the blood bank. The girl loses consciousness and Mitsugu takes her home... (Source: Official Website)

A spin-off from Teekyuu which centers on the daily life of Nasuno Takamiya, the exceedingly airheaded school tennis club member in Teekyuu, and her friends.