The first POD is in 1939. Although Germany invades Poland with the Soviets as OTL, Hitler gets killed off by an assassination soon after, replaced by Goering. While still an insane, megalomaniacal Nazi, Goering makes less idiotic foreign policy decisions than his predecessor, and keeps the alliance and importation deals with the Soviet Union. German spies instigate British paranoia about the Soviets, leading to Operation Pike against the seemingly-allied Soviets and Germans, aimed at Soviet Baku. This escalates into a proxy conflict in Iran and India.
Meanwhile, Japan invades Britain and France when they declare war on Germany. French Indochina falls, and later British Malaysia and Singapore, the latter partly due to luck on the part of the Japanese, but also because the British are distracted in the Mediterranean, Iran, and the North Sea after the fall of France.
From here, the Japanese have a clear advantage in the South China Sea. While Germany strong-arms the Netherlands into the Axis in Europe, Dutch Indonesia (with some resistance) becomes the main oil supply for the Japanese Empire after the US restricts oil exports to Japan. Japanese troops enforce this. However, by this point, FDR has died, replaced by Henry A. Wallace. This, and a series of scandals by J Edgar Hoover lead to a surge in isolationism.
The communist movement in China is particularly unlucky, with Mao Zedong killed by a Japanese raid. From here, largely unchallenged in their waters, the Japanese focus on defeating British naval presence in Australia, and also distracting the British in India by supporting Azad Hind.
After a long series of events in Europe including Turkey joining the Axis and being aided by Erwin Rommel against the British, and a less-"puppeted", more sovereign 'Vichy' France with not-insignificant control of its colonies participating in the Italian invasions of Africa, the British and Germans start approaching stalemate in German favor. Economic troubles from the lack of conquests and confiscations in the east, and pointless naval war with Britain, lead to a military coup in Germany, which removes the Nazis from power. In Britain, extraordinarily unlucky Winston Churchill who has lost France, French Algeria, and British Malaya, is replaced by Clement Attlee, who agrees to peace with the new government of Germany. This allows the British to push back against the Soviet invasion of Iran and India, after which peace is made with Stalin.
With the big powers at peace, military-industrialist Germany prepares for an invasion of the Soviets from the west, while the IJA, who has largely prevailed in China, prepares to invade the Soviets from the east.
Japan is able to hold their ground against the Soviets after declaring war, although without much forward success. However, once Germany, who has assembled puppet states from France to Romania to Hungary to Italy to Turkey, begins their invasion, the Soviets are now fighting on two sides.
Japan is able to take control of Mongolia and southeast Siberia, while the Germans, with more allies and manpower than OTL, push into European Russia. Stalin is killed.
The end result is a collapsing Soviet Union, with the Japanese establishing a defensive frontier for their territories in China, and the Germans pushing toward Moscow. In late 1945, Japan has the upper hand and nearly secured ceasefire with the British and Soviets.