For certain reasons, Rune's entire family was expelled from a prestigious group of families, the Cosmos Federation. Left as that fallen family's sole descendant, Rune decided to run away at 10 years old and start her life anew as simply but a maid for the Moore's. She has now become the Moore's successor's closest maid, but her life takes a sudden turn when her mistress declares she will get married — and to a successor of one of the Cosmos Federation's families no less?!