The Secret of Reincarnation

In my world, ghosts aren't anything to be afraid of. They are simply "people" from another world, and we can live together in peace. Ghosts pass through reincarnation to enter the human world, while people go to the underworld after death. It seems like a simple cycle of life and death, but a secret unknown to anyone appears to be hidden behind it. What unspeakable truth lies beneath reincarnation's false mask? Is reincarnation a necessary evil, or is there more to it? Join the novel's protagonist as he uncovers the truth behind reincarnation.