This is my first timeline. I hope you enjoy it. This is the introduction to my TL. I'll update later.
During the early 20th century, America followed an isolationist policy (Monroe Doctrine) and did not intervened in World War i nor World War ii.
Japan joined the league of nations with countries such as United Kingdom and France. Germany, Italy and the other Axis Powers won World War II. Japan was defeated.
After the war, Japan was occupied by Germany.
After that, a Cold War was established between Germany and the Soviet Union.(In this alternative Hitler cancel his plane to invade the Soviet Union)
Seems implausible or even impossible IMO. You're completely ignoring the butterfly effect.
First off, America
was isolationist. Roosevelt was trying to drag the US into the war kicking and screaming, without success until Japan attacked Pearl Harbor and the Axis declared war which was a god sent for FDR (some go so far to say that he knew what Japan was up to, but did nothing because he wanted to get into the war to support the Brits). The same applied to WW1 where it took the Zimmermann telegram (and it's arguable whether or not it was a British ploy)
and unlimited submarine warfare to get the US involved.
First off, if America remains neutral in WW1, it's very likely that we'll see a compromise peace between the Central Powers in the Entente. Germany loses its colonies and Alsace-Lorraine but keeps its gains from the Brest-Litovsk Treaty, no war reparations and no arms limitations. Germany will have it tough the first few years with communist unrest and a deep recession, but the Nazis will likely not rise to power if Germany is not humiliated after WW I. In such a situation, the German Empire keeps on going and remains powerful. They will likely not tolerate the Soviet Union for any longer than they have to. Once they have served their purpose as communist bogeymen to keep Germany's new Eastern European puppets in line, they're goners.
Thirdly, if Hitler does come to power(extremely unlikely), he will never give up his Lebensraum goals. It was his stated desire to conquer 'lving space' in the east for Germany which would be settled and economically exploited by Germans and any other Germanic/Aryan races that are willing to work with the Nazis. You would have to remove Hitler from power to prevent his invasion of the Soviet Union.
Fourthly, how on Earth is Germany going to occupy Japan? It's way too far away from Germany and has a superior navy and Germany has no naval bases in South East Asia and can't hurt them. Going by land is equally impossible as the Soviet Union is too big to conquer entirel; the poor infrastructure in much of Russia coupled with the enormous distances will be hell for Wehrmacht logistics. In any nazi victory scenario, Hitler will have to settle for a Brest-Litovsk like peace at best (maybe a bit more) or 1939 borders at the worst with many variations in between. And even if the USSR just disappeared (which belongs in the ASB forum btw), the problem of Japanese naval superiority and air power is still there, rendering the chances of an invasion of the Home Islands nil.
Don't take this criticism harshly. You should to research first and write something more realistic. If you do press on with this, I recommend you put it in the ASB forum. As an example of how to write timelines, you should read some other timelines too (like the ones in my signature for example).
Oh, and welcome to the board.