One World, Four Countries

In the depths of the distant universe, there is a planet called Lapola. There are only four countries on this planet - the country of teenagers, the country of youth, the country of middle age and the country of old people. The four countries are strictly divided according to age. Everyone on this planet is born in the Kingdom of Youth. After the age of 18, all memories are erased and sent to the Kingdom of Youth by the space remote transmission system. As one grows older, a person has to go to the four countries of Young, Middle, and Old respectively. And when a person dies, although his body dies, his soul remains. The soul will be infused into a new body and become a baby. Repeatedly and endlessly