That non-aggro pact looks a little familiar.
But it should add this: the 2 signatories cannot allow their allies to attack the other signatory from their territory.
That is, for example, UK bombers based on Russian soil cannot attack Japanese units, nor land in Russia from such an attack from elsewhere.
The treaty should remain in force for as long as the power gaining the right to attack wishes. For example if Berlin falls Russia and Japan are only at war when Russia declares war on Japan, which it can do at any time. Japan would not have the right to attack until Russia declared war, or until it’s own criteria were achieved.
(Supposing Russia wanted to see a powerful Italy beated down a bit, or rebuild it’s own forces up after a hard German campaign, before risking war with a bloated Japanese monster.)