Mermaid

Setting: 

This story takes place in a country near the sea.

Conflict:

The boy argues that a fish is actually a mermaid. He gets arrested because the government prohibited citizens to imagine something freely. Eventually he was confined and had his thinking manipulated.

Climax:

The boy got into the prison, and due to the electric shock his mind was being controlled so as to erase his imaginary thoughts. After that, he returned home but found a fish and no longer was able to see a mermaid.

Symbol:

Fins - Even after being manipulated and starting to forget about the mermaid, he still remembered the existence of fins. I believe this is because fin gave his imagination a great impact of freedom, as it allows you to go everywhere. 

Irony:

The ironical part is that he never changed his insistence through the examination on him, however, when he returned to his house and saw his water tank there were no mermaid.

Theme:

Freedom of having a distinct thought. Since the boy was the only one that saw the fish as a mermaid, he was discriminated and that made him feel isolated. I think this is a typical stereotype especially in Japan that everyone need to be the same. However, the movie insists that being unique is not a wrong thing.