High school student Haru Yoshioka is bored with the monotony of life. One day, she saves Prince Lune of the Cat Kingdom from being run over by a truck. As a token of gratitude, the Cat King sends her "presents" and invites her to the Cat Kingdom to become Lune's wife. Haru's inability to properly communicate with the cats leads to the misunderstanding that she has accepted the proposal. As Haru ponders on ways to escape the predicament, a mysterious voice instructs her to search for the Cat Bureau. However, not long after she finally arrives at the bureau, a horde of cats swarms in and forcibly takes her to the Cat Kingdom, along with a member of the Cat Bureau. Concerned for their safety, owner of the Cat Bureau, Baron Humbert von Gikkingen, follows close behind. The more Haru immerses