The Soviets trivially took the Kuril Islands and they can trivially defeat Japan if they so desire. China's also really interested in Okinawa independence. Both countries have appealed to arguments on liberating indigenous populations to hint at future military action against Japan.
It's a future war zone through and through, especially now that their PM is LARPing as Hirohito reincarnate.
Japan defeated the Russian navy in 1905. I guess that means that the Empire of Japan can trivially defeat the Russian Empire if such political entities cared to exist anymore and if the result of a past confrontation was a true benchmark of the current capabilities of the respective armies and economies.
Can you clarify this for me: the Soviets don't exist, so how can they possibly take the whole of Japan - in some future?
If you mean Russia, then no.