Why should Russia early attack Japan? Will Russia, or one of his Allies get any advantages from that attack? (China maybe…)
Why should Japan crush the russian infantry masses? The way through siberia is much longer, then through china. And the main operation targets are China, India and the south-west pacific.
I think the best way is a non-aggression-pact like 1941. Both sides are free to talk about the conditions (for example no jap industrial complex in Manchuria vs. no soviet infantry in Amur).
I think an early war is too risky for both sides.
Don’t trust the dices!
Russia may loose vital IPC from the far east, or japan looses aircrafts, urgently needed in the pacific.