Actually I'm just gonna scrap this idea. This whole squabble over something silly just killed my mood.
<Snipped quote by TwilightDragon>
I'm honestly not seeing how setting it in Japan is original or makes any difference in this case. There's no real need to set it in Japan when it'd actually make more sense to set it in Europe so the european mob family doesn't stick out like a sore thumb considering Japan has its own organized crime with a long history and traditions. Fiction doesn't have to correlate to reality 100%, but there is such a thing as good sense, and having Japanese organized crime take the scene in a story about organized crime set in Japan is sensical. You'll notice other people have already pointed this out, this isn't an isolated thing.
If I'm coming into your interest check and taking the time to post, I must clearly be interested. I'd be okay with magic organized crime, whether set in Japan or otherise, I think it's a fun concept to play around in. I'm simply explaining that hey, this one particular bit doesn't make a whole lot of sense and can be easily fixed so you don't have people asking why the game set in Japan is focused on an organization of european origin which somehow took over a country known for being isolationist and straight up ethnocentric throughout its history. Fantasy might not have to stick to the rules of reality, but it should at least be internally consistent.