Simply not enough time between POD and 1945 to force a Japanese surrender.
The least ASB I can think of is....
Heer generals revolt against Nazis, offer unconditional surrender to the Wallies only, and maintain a defense against the Soviets until Germany is occupied.
Stalin, feeling cheated out of a German occupation zone and Western Poland, floods troops into Korea and China and begins preparing for an invasion of Hokkaido.
After Leyte, Stalin offers Japan generous surrender terms for a Soviet occupation just to get back at the Wallies. Japan accepts- effective 12/31/1944.