Bitcoin is in many main languages but not Japanese. Why would the guy who created it not make it in his own language? Don't you find it suspicious MtGox is in Japan?
Also the project really isn't a success. A lot of progress still has to be made. Security is still an issue along with sites still growing. Anyone ever even talk to him? I'm not saying he isn't real I'm just putting this out there.
Really? So, how did you get to know that whoever it is that Satoshi Nakamoto was is not someone from Japan? You don't know which country he or they are from, so why assume that they are from any other country and should named the cryptocurrency in their own language when you are not sure of it. They might even be someone from Japan that created it, no one has an idea.
It is also possible that it can he someone from any other country around the world and maybe at the moment they were creating Bitcoin, the name came to their mind and they felt it was the right name for it?