Natori Nono is a very tough school-girl, she lives with her widowed mother Ayame and her younger brother Takumi in a very small apartment, where she does all the chores. Her boyfriend wants money from her, because he's really poor, too. But one day, Nono discovers that her mother remarried! She married Ichijou Hayato, the owner of the 'Ichijou Group'. Now, Nono lives there (in unaccustomed riches) with her mother, her brother, her stepfather AND her new stepbrother: Ichijou Kasuomi (his father calls him Omi-kun)!!! At first, Nono thinks Kasuomi is not nice. But what will happen next?