Kaishin is a gigantic planet similar to the Kaiohs'. On Kaishin, a gigantic tree on the planet known as the World Tree spawns the Core People from its fruit. The Core People go to a castle that's similar to a school and learn a variety of things. The population of the planet is about 80.
The World Tree (界樹 Kaiju?) is a gigantic tree found on Kaishin that grows fruits which is able to bring life to the Core People. Shinjin are selected to become a Kaioh or a Kaiohshin. However, a Kaiohshin is only selected if you are born from a golden fruit, which is rare. On occasion, Core People with evil hearts are born and fall under the Makaiohshin.
The Core People go to a castle that is similar to a school to learn a variety of information.