Ponyo is a goldfish who lives in the sea, and has an over-protective magician for a father. Soon Ponyo runs away from home and is rescued by a five-year-old boy named Sosuke. As she wants nothing more than to understand what it's like to be a human being, Ponyo uses magic to transform into a human girl, and the two begin to form a special bond. However, this magic results in drastic consequences, and one final test stands in Ponyo's way before she can truly be human. Can Ponyo fulfill her dream, or is she destined to return to the sea?