When Ryuu is born his tribe tries to sacrifice him to a Tyrannosaurus named Shirano because of the color of his skin. He is however saved by a monkey who raises him as her own son. Meanwhile Ryuu's mother has left the tribe and is out on a quest to find Ryuu.
16 years later Ryuu meets a girl named Ran who was sold to the tribe Ryuu originaly came from. The tribe is not happy to see Ryuu alive and tries to sacrifice him again, this time by burning him alive. Before they can get the deed done the tribe is massacred along with Ryuu's adoptive mother by Shirano. Ryuu then sets out on a quest together with Ran to find his mother and Ran's brother Don.
