When Haru Yoshioka rescues Prince Lune of the Cat Kingdom, she unwittingly gets entangled in a feline proposal. Miscommunication leads her to accept the prince's offer, prompting a journey to the Cat Kingdom where she grapples with her transformation into a cat. Guided by a mysterious voice, Haru seeks the Cat Bureau for help, only to be whisked away by the feline inhabitants. In her quest for self-discovery and a way back to her human form, Haru navigates the whimsical world of cats, with the enigmatic Baron Humbert von Gikkingen by her side. As she embraces her adventures, Haru learns valuable lessons that shape her newfound confidence and identity.