In a futuristic era, "The World" is a peace-bringing entity. Though no one knows its location, it has watched over Earth for so long that war has become merely a fable. The airship Norn's task is to deliver nine ability users to The World.
After collecting the last person, Norn takes off. Included onboard are eight men and three women—Koharu, who has finally escaped her loneliness and detests her destructive power; Mikoto Kuga, born to a noble family, who uses her barrier skill to protect the Norn and those it carries; and Nanami Shiranui, whose ability only brings pain, and who wishes to die for a past sin she has committed. While en route, suspicions arise amongst the passengers when they realize there are too many people onboard.
As they try to determine who has snuck aboard, the ship is attacked by an unknown assailant aiming to stop the Norn's progress at all costs. From this chaos arises questions: why were they granted powers, and what must they do once they reach The World?