Since you can't live in both places (at least not comfortably), you should probably just live in Russia or Japan and get a friend of the other nationality.

I guess you'd be better off livin in Japan getting a Russian friend. Russia and most Russians are awesome, but Russia, mostly, is not. But it may be hard finding a lot of Russians in Japan (not entirely sure), while I think finding Japanese in Russians will be easier (there's lots in Moscow).