With the powers of the Queen of the Cosmos weakening, a successor must be chosen to maintain balance across the galaxy. The current Queen and her aide select two young women from the Royal Smallney Girls Academy as candidates for the Queen Examination: Angelique Limoges, a cheerful and somewhat clumsy 17-year-old, and Rosalia de Catargena, a confident and dignified girl of the same age from a noble family. The two are transported to the Flying City, where they are each given a barren continent to cultivate and populate. The candidate who successfully develops her continent first will become the next Queen, while the other will serve as her assistant.

To aid them in this task, the candidates must seek the support of nine handsome Guardians, each representing a cosmic element. These Guardians possess powers known as Sacrea, which can help a candidate's continent prosper or, if used competitively, devastate a rival's lands. The Guardians include Julious, the wise Guardian of Light; Clavis, the gloomy Guardian of Dark; Luva, the warm Guardian of Earth; Oscar, the playful Guardian of Fire; Lumiale, the gentle Guardian of Water; Olivie, the flamboyant Guardian of Dream; Randy, the high-spirited Guardian of Wind; Zephel, the rebellious Guardian of Steel; and Marcel, the sweet and innocent Guardian of Green.

As Angelique navigates the examination, she forms friendships and potential romantic bonds with these Guardians, learning to harness her own inner strength and leadership abilities. The narrative explores her growth from an ordinary girl into a capable leader, balancing her rivalry with Rosalia with moments of mutual respect. A significant narrative choice emerges throughout the story: Angelique may continue her pursuit of the queenship, or she may fall in love with one of the Guardians, which would require her to forfeit her candidacy for a life of romance. The story unfolds across a series of tests and challenges as both candidates develop their continents, interact with the inhabitants of their lands, and ultimately determine the fate of the cosmos. Later portions of the manga follow Angelique after her ascension, as she rules a newly established cosmos and faces new challenges, including being drawn into a pocket universe called Arcadia where she must develop wilderness to free a mysterious being named Elda.