This story's main characters are a boy and a fish, and this is the story of boy who likes imagination. When he looks at the fish in water, he came to see the mermaid. They spent happy time. Then, he took the mermaid to the house, and he introduced her to his parents, but she looks only him. In that country, you weren't allowed to daydream. He took to the plice. The police did a lot of punishment to him to erase about her memory. At first, he didn't forget at all, but finally, he forget about him. He was very disappointed. But a fish became mermaid in the ocean. At the end, he disappeared with her into the ocean.
In my opinion, this story is very sad. He loves her, but it doesn't go as his wishes. I think that Tezuka Osamu's story is very interesting.