"They say the sun never sets on the British Empire. They will soon learn a lesson that Icarus knows all too well." -Tomoyuki Yamashita

Following their successes in China, the IJA decided to temporarily rest and upsize their military rather than continue a rapid expansion. Military provinces and governors were put in place, and actual governments were made in the newly annexed Chinese states. The units lost in the Chinese Domination War were quickly replaced, and even expanded upon. The Kwantung army went from 300,000 to around 750,000 between January of 1939 and September of 1940. For two years, industry was also rapidly created in China, and Manchukuo and Sensaisho were provided their own armed forces underneath the IJA. The Japanese economy kicked into wartime production as many factories were made to produce tanks, planes, and ships rather than automobiles or other more comfort goods. By the end of 1940, the IJA had increased from around 800,000 troops to close to 2 million fully armed and trained. Publicly, the Japanese Empire spoke poorly of the Nazi regime, but privately coordinated with the Germans to prepare for the full war. On January 3rd, 1941, the Japanese army launched its attack on Vietnam and Thailand, led by now General Yamashita of the Kwantung army.

The War of French Annihilation
The Franco-Japanese War, as called by the Japanese media, saw the quick capture of Hanoi by January 18th, with coordinated naval attacks along the coast that quickly secured Northern Vietnam. Bombing and naval bombardment campaigns, combined with a fierce Japanese offense, collapsed conventional fighting from the Vietnamese French armies in the next two weeks. Adapting tactics from Shaka Zulu into a modern setting, Yamashita split his army into 4. The horns, which consisted of mainly motorized units, would move to the left and right of the main army, capturing towns and eventually cutting off the enemy army. The chest, which comprised of the bulk of his army and its infantry, moved almost directly for the enemy position, army, or city, attacking it head on. And finally, the loins, which served as reserve troops who were 40+ and sent to support any of the previous three formations that required bolstering. They were also left behind as garrisons in captured territories. This strategy awarded him a major victory at the Massacre of Vientiane, where a number of French forces hoped to pin and defeat the Japanese army. The French were encircled and destroyed with ease, and prisoners were used as meat shields in other major battles. By March 23rd, the French had surrendered in Vietnam and Thailand had almost completely fallen.

The Continuation War
With the fall of Saigon and the surrender of Thailand soon after, the IJA high command greenlit operations against the British Empire. March 25th saw Japanese, Chinese, and Manchurian troops pour into Burma and Malaya. The Battle of Singapore saw Yamashita attain almost mythic status as a military commander, and was appointed to lead the attacks into the British Borneo and the Dutch East Indies by Tojo who by this point had become Prime Minister. The Burma campaign was bloody, as Indian troops were easily able to reinforce their lines in copious amounts, but the Japanese had been fighting for 3 years by this point and fought for every foot. The war likened to the Vietnam conflicts OTL. The war bled the Japanese resources dry, but the discovery of a large oil field in Manchuria rejuvenated the front in June, and the capture of Naypyidaw came a week later. The news of Japanese campaigns in Southeast Asia shocked the world, and was met with embargoes by the United States, but no outright aggression or military action. The steel embargoes hit the hardest, and forced the Japanese to sue for a peace with Britain in which Burma became independent, and the other British territories they took were annexed by Japan. On June 7th, Japanese planes roared over the Indonesian islands, bombing major troop installments as armies landed in Sumatra, attacked south into Borneo from Malaya, and the IJN completely blockaded the Dutch East Indies from receiving outside aid. The Dutch, who had already lost their homeland to the Nazis, quickly surrendered by June 22nd.

The Aftermath
On June 26th, 5 men met in Tokyo to discuss the future of Imperial Japan. Their identities were Emperor Hirohito, Prime Minister Hideki Tojo, General Tomoyuki Yamashita, Admiral Isoroku Yamamoto, and General Shunroku Hata. Over the course of 3 days, they debated on the Imperial policy of expansionism and militarism, the goals of their very own Japanese Pacific Empire. They came to the conclusion that this goal was technically filled, and moved on to the topic of the Nazis. As the highest ranking members were aware of the holocaust, they evaluated the entire situation and came to the conclusion that their enemies no longer aligned, and prepared to sever the alliance and exit the axis powers. Finally, they moved to the topic of the United States, where Yamashita and Yamamoto voted to declare open war against the nation for their transgressions, while Hirohito and Hata voted against it, with Tojo deciding against the action after a brief deliberation. On June 30th, Japanese officials met with American and Soviet diplomats to inform them of what little intelligence they held, and of the holocaust. Predictably, both parties were outraged and this led to the entrance of America into the second world war. The official exit of Japan from the World War II in 1941 allowed for 4 years of extra time to rebuild industry and infrastructure that many participants never received, and further development of the navy and airforce without major battles allowed Japan to quickly become one of the most powerful militaries in the world. In response to their help and information, the United States officially lifted embargoes from Japan.