My interpretation about this Tezuka's film we have watched yesterday, is simply,
people have the right to imaginate, We are free to imaginate. Whether your
imagination may not be true or not, we should keep imaginating. Don't let anyone rule your right.
Well, I guess that man was in love with the mermaid. But the Mermaid only existed in man's imagination.
Since imaginating is prohibited in his country, he was banned from imaginating, and thinking about the mermaid.
Eventhough no matter what happened to him, he did not stop imaginating about the mermaid, so the imagination about the mermaid
became true, they lived happily ever after.
If you keep believing, it becomes true.
shoichiro