Living peacefully on the space colony Juno, twin brothers Thor and Rai come home to find their parents murdered. They are quickly taken away and abandoned on Chimaera, a dangerous world ruled by plants and usually reserved for criminals. The people there go by survival of the fittest, and have separated into groups called Rings. Young Thor learns that the only way to get off Chimaera is to become the Beast King by defeating the leaders of all four Rings. Determined to find out why he and his brother were exiled and escape the savage planet, Thor sets out to become the Beast King.