Special Rules on Classes
Each class section has any special rules and fluff information for how they work in the setting. GoHyaku uses the Emerging Guns rule for firearms. Advanced Firearms are readily available but only to characters with appropriate backgrounds relating to the Tabernacle.
A Word of Advice
While all of the classes function the same as they do in normal Pathfinder, they work very differently fluff-wise, especially the Divine classes. You shouldn’t need to know all that much lore to play one effectively, but be ready to be dragged into the complicated political machinations of the NPCs at any time.