Obviously inspired by The Little Mermaid, Ponyo tells the story of five-year-old Sosuke and his mom Lisa. They live in a friendly coastal town in Japan, where the main industry is fishing. Sosuke’s dad Koichi is usually off on his boat working. There’s an environmental message here of course because that’s a favorite of director Hayao Miyazaki. But while humans are shown damaging the seabed and gathering fish, it’s clear none of it is done with malice. Humans need to exist like all beings, and this is how they understand the way to do it. Human kindness is all over the story, as Lisa works in a senior citizen's home that’s full of warmth despite the sadness of getting old. Some of those scenes are really gut-wrenching, and you may need to explain a bit about old age to the kids watching with you.
Kindness leads the way when Sosuke one day encounters a strange goldfish and saves her from being trapped in a discarded glass jar. The goldfish turns out to be Ponyo, who escaped from her own absent-minded father. Sosuke and Ponyo become fast friends, but there’s more. Ponyo has an ability to change forms, and as you may have guessed from the Little Mermaid reference, soon becomes human, taking the shape of an adorable little girl.
In the world of Ponyo, none of the “real” humans question how a fish became a cute girl, and all accept her lovingly, especially Sosuke, Lisa, and the old folks at the retirement home. Problem is, a massive storm approaches the town, and from that comes the only semblance of threat in the story. Saying more would be very spoiler-y.