From the introduction:
Welcome to Gensokyo, a land on the boundary of fantasy and reality, a land where myths are true. A land where Western vampires and Eastern youkai – spirits from Japanese mythology – coexist, living by the power of belief and fear the humans hold of them. Here, under the watchful protection of powerful youkai and humans who wield magic and the powers of gods, a village of mankind thrives in relative safety, warded against the worst of natural disasters and violence. Here few fall in battle, as an agreement between youkai and the representatives of humanity keep battles non-lethal. It is the ultimate goal of the major powers here to ensure a careful balance between youkai and humanity; disrupting this balance would be exceedingly unwise for you. Be warned that while many people here are very silly and prefer play-fighting to serious battle, many of them are tremendously powerful, and you would not like to force them to fight seriously.