From Viz:

When awkward schoolgirl Haru rescues a cat on her way home from school one day, the last thing she expects in return is to be honored by a feline royal family! Before she knows what's happening to her, Haru is drawn into a world inhabited entirely by talking cats--and recruited to be the next Cat Princess! Only the dapper cat Baron and his friends, a magical crow and a comical fat cat, along with a friend from Haru's past, can help her return home.