Jyu-Oh-Sei (Planet of the Beast King) is a manga series created by Natsumi Itsuki. The story started at the Balkan star system, located approximately 150 light years from Earth. Thor and his twin brother, Rai found their parents murdered in their house. Unknown masked men gas the children knocking them out after witnessing the suspicious death of their parents. The two 12-year-old young twins awake to find themselves on Chimera, a secret planet used as a penal colony where day and night last 181 days each and the planet marked by extreme weather patterns. Chimera is also known as the Planet of the Beast King. Given only a beam knife and a smelly satchel, they wander together in search of civilization on the primarily plant based world. The boys are not only attacked by the planet's carnivorous plants, but also by a group of humans whom they eventually learn are the "Wildlings". After a chase, the leader of the hunters, Zagi, orders his man to back away so he can give the brothers a tour of the planet. He explained that their group contains mostly younger adults and kids who were abandoned by the Rings. In Chimera humans are divided into groups called Rings based on their skin color, these Rings are the Ochre Ring, Sun Ring, Blanc Ring and Night Ring. In order to escape this planet, one has to become a Jyu-Oh, which is the King that lords over all four tribes.

The Wildlings beat Rai after he spills water, a precious commodity there. When Zagi warns Thor that Rai will hold him back and that the others will "cull" him during the next night phase, the boys leave. While trying to escape an attack from the Ochre Ring, Rai is killed by one of the plants. Thor is rescued by a woman named Tiz, who along with a man named Third, take him to the Ochre Ring. After treating his wounds, they explain the planet's politics to him. He learns that each ring is led by three people: the Top, Second, and Third, with the Top as the leader. He also learns that due to women making up only 20% of the population, they are considered extremely special, live apart from men, and are the ones who get to choose their husbands during the "Month of Joining", a request a man is generally not allowed to refuse. Despite his refusal, Tiz chooses Thor as her first husband.

Tiz was originally the Second of the Sun Ring’s female clan. Immediately after meeting Thor, she takes a liking to him and tries to make him her husband, much to Thor's disappointment. Tiz even left the Sun Ring, after Thor fought with Chen and won, just to be with him.

Thor and Tiz decided to form their own ring but they need at least 3 members, Third in surprise volunteer himself to be the 3rd member of the group. This guy is known only as Third as he is the third in command of Ocher Ring. He acts as a supporter of Thor when he declares that he intends to become the Beast King. This guy is very mysterious and his motive will be revealed at the last few episodes of the story which is using Thor to complete a mission given to him by his commander so that he could go to Earth. He will be very disappointed at the last part when he will discover that Earth had been destroyed 130 years ago. He will commit suicide in order to force Thor into escaping from Hecate.

There are lots of exciting scene in the whole 11 episode so better watched it. There’s lot of twist in the story in Thor’s life. I feel so sorry for Tiz, especially as Thor’s immediate infatuation with Karim was quite rapid and perhaps unintentionally amusing. The whole story is great, there’s so much adventure in it but I feel not so happy with the ending. I think the ending is not complete there’s something missing in it.