From the introduction:
You think you’ve seen Bizarre? Get ready because you ain’t seen nothing yet.
Welcome to the world of Jorge Joestar. It might be very familiar to you if you’ve ever heard of another sort of Bizarre Adventure but this place has a number of differences from the main adventures of the Joestar family.
In this World, there are thirty-seven universes. Each of these universes has an infinite number of alternate timelines and dimensions. But out of all this time and space, only three places really matter. The first is the original universe, the one where Dio Brando the Vampire waged war on the Joestar family for generations. The second is the world of Jorge Joestar, the son of Johnathan Joestar who grew up in the Canary Islands rather than returning to England and the last is the world of Joji Joestar, the adopted scion on the path to becoming a Great Detective.