Duan Yu is a fictional character from the popular Chinese martial arts novel "Demi-Gods and Semi-Devils," written by Jin Yong. He is known for his carefree personality and unique ability to learn martial arts techniques quickly, often without formal training. Duan Yu is the prince of the Dali Kingdom and is characterized by his kindness and strong sense of justice. Throughout the story, Duan Yu embarks on a journey filled with adventure and romance. He becomes entangled in various conflicts involving different martial arts sects and seeks to protect those he cares about. His relationships with other characters, such as Wang Yuyan and Xuzhu, play a significant role in his development and the overall narrative.