If Europe remained stable, Japan would have no confidence to launch its southward strategy. The United States and East Africa also had to be taken into account. There was no need to overthink it—even if Japan intended to deal with the United States and East Africa, it would only place those two countries last on its list.
As for Japan not becoming enemies with the United States and East Africa, that was simply impossible. Japan's ambition was to dominate the entire Far East, and neither the United States nor East Africa could possibly allow such a vast region to fall entirely under Japanese control.
The relationship between Japan and the United States and East Africa resembled that between the Soviet Union and Germany. Peaceful coexistence was impossible; war was merely a question of sooner or later.
The Japanese Government was also crystal clear on this matter. It understood perfectly well that the United States, East Africa, and the Soviet Union would never stand by and let Japan rule the Far East, so it had to prepare all kinds of contingency plans for dealing with those three countries.
From this perspective, the pressure Japan faced was now far greater than Germany's. If Germany could settle Europe's powers, it stood a strong chance of shutting East Africa and the United States out of Europe.
It was only because Germany had been unable to take Britain in the previous life that the United States had been able to use Britain as a springboard and, together with the Soviet Union, deliver Germany its final fatal blow.
Looking at the present, Japan's most achievable strategic objective was to seize the South Seas, take the two choke points of the Strait of Malacca and the Sunda Strait, and then engage East Africa in a long-term struggle.