"Planet of the Beast King") is a Japanese manga series written and illustrated by Natsumi Itsuki.

[2] The series deals with the adventures of twins Thor and Rai, who live on space colony Juno, a planet resembling Earth, until they are abandoned and sent to Chimaera, a secret planet dominated by extreme weather patterns which is used as a penal colony.

Two 11-year-old twins, Thor and Rai, live on the space colony Juno until they come home to find their parents have been murdered.

The unknown assassins drop Thor and Rai on Chimaera, a secret planet used as a penal colony.

After several years Thor faces off with Zagi who has violently taken over the Blanc ring and is determined to rule over and change Chimaeran society.

Odin tells Thor he is a genetically engineered human created from the DNA of all the previous Beast Kings.

Finally, Odin reveals a long-kept secret: that Earth was destroyed by an asteroid collision long ago, and humanity cannot return there, so they must adapt to survive in the Balkan Star System.

However, Odin's plans involve dissecting Thor in order to mass-produce more genetically engineered humans capable of surviving in Balkan, and terraforming Chimaera, which would kill the planet's current inhabitants.

The prisoners adopted a feudal society and divided into four groups of humans, called "Rings" that act as governs on the planet.

If an individual successfully defeats the Top of all four rings they become the "Beast King" who gets to be pardoned for their crimes and allowed to reside on Hecate.