At the moment of Ryuu's birth, his tribe attempts to offer him as a sacrifice to a Tyrannosaurus named Shirano due to his skin color. However, a monkey rescues him and raises him as her own child. Meanwhile, Ryuu's mother has left the tribe and sets out on a quest to find him. Sixteen years later, Ryuu meets a girl named Ran, who has been sold to the tribe that originally belonged to Ryuu. The tribe is displeased to see Ryuu alive and tries to sacrifice him again, this time by burning him alive. Before they can carry out the act, Shirano massacres the tribe and also kills Ryuu's adoptive mother. Ryuu then embarks on a journey with Ran to locate his mother and Ran's brother, Don.