Chiu Dai is a prominent supporting character in the anime and manga series 'Dragon Quest: Dai no Daibouken.' He is a talking mouse who initially appears as a humorous and somewhat cowardly character, but proves his bravery and loyalty as the story progresses. Chiu becomes the leader of the 'Beast King Commandos,' a group of animal warriors, and plays a key role in supporting Dai and his friends on their journey. His growth from comic relief to a courageous ally is a notable aspect of his character.