On May 8, 1945, Europe came out of World War II. Regarding Oceania and Southeast Asia, peace arrived several months later on September 2 when Japan at last turned herself in. Other than one man, that is. WWII finished for him only in 1974.
Our drama starts in the Philippines, a Spanish colony until the Spanish-American War of 1898. To put it briefly, the Spanish lost and the Philippines turned American territory.
Ahead to the 20th century fast forward Taking Oceania and Southeast Asia, Japan sought an empire right next by. The issue was that different European countries owned practically all of it.
Japan so formed an alliance with Nazi Germany. With the later wreaking havoc in Europe and North Africa as well as threatening the British Isles, well... that took care of the British.
And Britain distracted meant that all of her colonies were vulnerable. Ditto with the Dutch colonies and French-Indochina since France and the Netherlands early on in the war fell to the Germans.
That left the American territory of the Philippines; what then to do? Simply said, destroy its Pacific Fleet and bomb Pearl Harbor on December 7, 1941.
Ten hours later, December 8 Japan attacked the Philippines while the Americans were still extinguishing flames.
Japan's central location provided the staging ground the nation required to attack the rest of the region. While the Filipinos produced outstanding (albeit reluctant) slaves, its huge resources also fueled the Japanese war effort. But there was still another issue.