From the SEG:
"Inside the giant ball that is the DB cosmos is a world called Planet Kaishin, which is where the Kaio are all born and raised. This planet is like a giant version of the Kaio Planets that North Kaio and the others live on. On it is a gigantic tree, the Kaiju, and the Kaio are all born from the fruit of this tree, as Shin-jin. The population of this planet is about 80. The Shin-jin are genderless, and their average life expectancy is said to be 75,000 years. They live leisurely lives, studying various things at a school-like castle. But whenever one of the Kaio on the Kaio Planets passes away, they draw lots among themselves to choose who will take that Kaio’s place and become the new Kaio. The Kaioshin, however, are chosen only from among Shin-jin born from a special golden fruit that is particularly rare. Occasionally there are delinquent Shin-jin with evil hearts, and they go to be with the Makaio."