Anyway, this kind of sentence is pretty hard to put together unless you know what kind of implication you want it to have; Japanese is pretty tricky and delicate like that. Perhaps "日本に威嚇をするTOUR" (Nihon ni ikaku wo suru TOUR) or "日本が威嚇をされてるTOUR" (Nihon ga ikaku wo sareteru TOUR) would be the two most natural choices I can come up with, with the info you provided in the OP. The first one means, well, "threatening/terrorizing Japan tour" and the second one means the same, essentially, but without the implication that it is you guys (the band) unleashing the terror, ie. Japan is being terrorized, but without a human agent, ie. "Japan is being terrorized, tour". (Grammatically, Direct Passive).
As for the Okinawan part.. Well, I am currently a 3rd year Japanology major, and while we have shortly covered the Okinawan "dialect", I can tell you that it is (not that there is only one, either) so far away from the other dialects that it isn't really Japanese anymore, as we know it today. Perhaps I could help you with that within a year or so, but I just started my 3rd year, and while we are about done with the modern Japanese studies (parring mastering other dialects such as kansai-ben), we haven't covered all the Okinawan dialects much if at all yet.
