Hm... I guess the USA should be fine, I certainly know more about the US than Japan in terms of, y'know, real knowledge. And, man, as for magic in the US? The plenty of urban legends, myths and folklore could be incorporated onto this or we could use, for cultural purposes, magic could be tied to Native American tales and elements. Although it would be a lot more ritualistic and less inmediate. (Example: Magic circles, chants and such, not: *ZAP, PEW, ZAP*)