In a alternate timeline Gods made something called the Divine Network creating Patrons, and other things to counter demons making new races such as Vampires Werewolves and Undead. During the Sengoku Period in Japan there was nonstop fighting between clans, which caused the other races to get excited and join in on the fun. Europeans found the conflict profitable. Vampires found it a way to quench their thirst. Werewolves found it to be fun. And the undead found it to quench their hunger.