Five separate worlds—Black, White, Green, Red, and Blue—are linked by the "Halo" and exist in a harmonious balance. However, the Halo suddenly opens in an event known as the World Connect, threatening to destroy the universe. Coming under attack by Ouroboros, an alien species that wishes to accelerate the universe's end, the five worlds recruit girls with special abilities called Exceed to defend against them. Saya Sougetsu, a young girl from the Blue World of Earth, is one such individual able to wield Exceed power. Believing this to be her chance to make a difference, Saya eagerly joins the defense force. There, she meets Amane Ayashiro, another girl from Earth, as well as a selection of fighters from the other worlds. Faced with a formidable foe, the girls must prove that their newfound bonds are strong enough to save the future.