Ningyo
La Sirène ／ La sirène ／ Mermaid ／ Sirena ／ Русалка ／ 人魚
Description
In a fictional place where using the imagination is banned, a boy saves a fish, which surprises everyone by turning into a mermaid. The boy is arrested for imagining this "nonsense", and is robbed of his imagination as punishment. (Source: Anime News Network)