A white Transvaal lion and the protagonist of the story who, in the original manga, is followed from birth to death. He believes that there would be peace between animals and humans if each understood the other. In the 1997 movie, the lion leads Dr. Moustache and his assistant to Mt. Moon, and he sacrifices himself by falling on Dr. Moustache's kris so that Dr. Moustache will have food and shelter from the cold. In the 2009 TV movie, Leo has poor hunting skills and is acrophobic, always leaping straight up instead of across gaps. In his attack on the facility, he overwhelms his dislike of heights.