On her way home from school, Haru spots a cat with a small gift box in its mouth attempting to cross a busy street. The cat fumbles the package in the middle of the road, but Haru manages to scoop the cat away to safety before a truck can hit it. To her amazement, the cat then gets up on its hind legs, brushes itself off, and thanks her very politely. That night, a feline motorcade replete with vassals, maidens, and Secret Service cats shows up at Haru’s door with the King of Cats. In a show of gratitude for saving his son’s life, the King showers Haru with gifts and whisks her away to marry the cat prince and rule over their kingdom. In order to find her way back to the human world, Haru must turn to the mysterious Baron von Gikkingen for help.