From the introduction:
This tabletop RPG system is aimed at giving players the experience of building and enjoying their own JoJo stories with the guidance of a Game Master, or GM. A group of players, ideally two to six, will take on a campaign involving encounters with a series of opponents, likely Stand Users, in dense, detailed battles that take more than brute strength to win.
If you hadn’t guessed, it’s based on Hirohiko Araki’s long-running manga JoJo’s Bizarre Adventure and its popular anime adaptations. Though familiarity with the series will help, these rules can be understood by people who’ve never read or watched it. This document is spoiler-free, but some canon characters may have character traits and Stand abilities outlined in the Examples.