Once a year, in an unknown world called "Dark SASI" is a celebration of all the great souls. The main entertainment are considered the "test of death".
Great souls throw out a book on this holiday, which falls into one of the many corners of our world.
Once the book gets into the hands of a mortal, he falls into a coma and his soul moves into the world of Great souls.
At this point, they begin their game by betting on how many times the mortal soul will be able to endure suffering.