The story centers around a spirited high school girl named Marika. She keeps herself busy with the space yacht club and her part-time job at a high-class retro café. One day, two men suddenly appear and claim to be subordinates of her dead father. They demand that she assume command of the space pirate ship Benten Maru. A privateer ship's compact was made during a war of independence a century ago, and according to that compact, the ship must be inherited by the captain's next direct descendant. Marika finds herself embarking on a new life as a space pirate.