Flounder is a supporting character in the anime film 'Andersen Douwa: Ningyo Hime' (Hans Christian Andersen's The Little Mermaid). He is a small, friendly fish and a loyal companion to the Little Mermaid. Flounder provides both emotional support and comic relief, accompanying the protagonist on her journey and facing danger alongside her. His caring nature and willingness to help make him an invaluable friend to the Little Mermaid, contributing to the emotional depth and warmth of the story.