Kiki's Delivery Service [Picture Book] by Hayao Miyazaki

Now that she's 13 years old, it's time for young Kiki to start tinking about her future. So one night, under the light of a full moon, she grabs her black cat, Juju, hops on her mother's broom and heads off into the night. The next day she alights upon a friendly oceanside city, and this, she tells her loyal and furry companion, is where she'll spend the next year learning how to become a real, honest-to-goodness witch.