Brief history of East Asia
East Asia was always very important for great powers and saw great changes since Weltkrieg until modern day. Japan was the only Entente power that came from Great War even stronger. Empire of Rising Sun saw chaos in Russia for great oportunity to seize important Far East port of Vladivostok. Japanese also didn't hesitate to take their chunk of Chinese cake during German intervention in China in 1920s. Two Japenese satellite states were established in those times: Transamur in Russian Far East and Fengtien Republic in Manchuria. While Transamur was led by Russian rogue admiral Aleksandr Kolchak, Fengtien Republic was administrated by local Manchurian warlords.
Germans intervened in chaotic China and restored Qing Empire under Emperor Pu Yi which was deposed during republican revolution in 1911. But Chinese Emperor was ruling only small portion of historic imperial China. Manchuria was taken by Japan, Tibet was de facto independent nation, Sinkiang and Yunnan were ruled by local cliques, Mongolia was led by Baron Sternberg, crazy Russian aristocrat that declared himself new Khan of Mongolia and even managed to occupy part of Trans-Siberian railway. Due to weak administrative power of Qing Empire, Germans established special colonial corporation in Southern China and named it Allgemeine Ostasiatische Gesellschaft, or AlgOstAsien GmbH in shorter version. This corporate conglomerate which operated in area de iure still administrated by Qing Empire, changed Southern China into place crawled with German companies that exploited local cheap labour and tested radical production technics.
When 2nd American Civil War started in 1937 after American President Huey Long was thrown out from office by military, Hawaii proclaimed independence and even brought most of American Pacific islands under their rule. But fortune quickly turned bad for King of Hawaii when Empire of Rising Sun, encouraged by weak American protest after seizure of Guam, demanded Hawaii to accept Japanese rule. Hawaii accepted Japanese demand.
It was year 1947 when rivatly between Germany and Japan in Asia reached the peak. In 3rd of December, Japanese Imperial Navy suddenly launched surprise attack on German fleet based in Singapore. Planes from nine Japanese aircraft carriers striked German ships in harbour, sinking five German battleships including SMS Amerika, biggest battleship of German Asiatic fleet. Three years of bitter war between two great powers started. Germans quickly sent strong parts of other fleets to reinforce Asiatic fleet. It was large handicap for Germany not to start larger construction of aircraft carriers several years before. This was another consequence of German traditionalist view on military that saw use of battleships and heavy cruisers as best option for naval warfare. On the other hand, Japan experimented with new naval technology since the end of Weltkrieg.
To preserve stability in Europe and Africa, Germany didn't drag non-Asian members of Mitteleuropa into war. Germany was aided by Princenly Federation, AlgOstAsien GmbH and Qing Empire. Japanese Empire was assisted by all members of it's military alliance called Greater East Asia Co-Prosperity Sphere: Transamur, Korea(granted independence by Emperor in 1940), Philippines(accepting Japanese protection during American Civil War) and Fengtien Republic. First part of war was fought on the sea. After destruction of their most advanced carrier SMS Graf Zeppelin and several capital ships in Battle of the Philippine Sea(June 1948), Germans knew they can't win the war on the sea. German Pacific islands quickly fell into Japanese hands one after another. In end of 1948 Germans concentrated on war in China. Beijing was twice captured by Japanese and then liberated by Qing troops, commanded by German general Alexander von Falkenhausen(working in China as Chief Inspector of Imperial Chinese Army and as Chairman of AlgOstAsien GmbH Board of Directors).
None of the sides could also achieve air superiority over China. Germans compensated unsuccessful naval campaign in the skies over China. Germany managed to counter wast IJAAF with changing China into one big unsinkable carrier. Luftwaffe payed high price to prevent Japanese from dominating skies over China. But it was not alone. Altough not all members of Mitteleuropa being in war against Japan, many of European nations sent unofficial aid. Many Austro-Hungarian, Italian, Lithuanian and Ukrainian pilots flew in their fighters under emblem of Luftwaffe. In 1948, Luftwaffe started with limited operational use of Messerschmitt Me 262, first jet-powered fighter aircraft. This aircraft was not produced in big numbers due to lack of testing and and many unsolved technical problems. Messerschmitt Bf 109 stayed most reliable German fighter until the end of the war.
Frustrated by lack of success on continent and in desperate need of resources to fed war industry, Japanese Empire invaded Dutch Indonesia in 1949, pushing Netherlands into German bloc. Weak colonial troops of Holland were not able to stop Japanese from seizing entire Indonesia soon. However, entire Royal Netherlands Air Force was soon taking part in dogfights over China. Japanese also attempted to land in Southern China and Indochina, but without success, thanks to land forces of Princenly Federation which were shiped to Southern China and German Indochina to defend those areas against Japanese invasion. Germans also managed to keep Singapure in their hands despite heavy Japanese air and naval bombardment. Japanese were pressing on Siam to enter the war, but Siam was paralized by peasant uprisings, sponsored by Bengal, what was great fortune for Germans.
In middle of 1950, it was more than clear this war is not going anywhere. Japanese occupied all German Pacific possessions, but were unsuccessful on Chinese mainland. Kriegsmarine was no match for IJN in direct combat, but Germans, hidding their ships in small Chinese ports, still waged irritating raids on less defended Japanese naval units and convoys. Germany also started with massive use of submarines in Pacific. But Germans didn't how long can they still bear burden of war in Asia. German economy, just getting back on feet after Market Crash in 1936, was in downfall again. Trade routes with Asia were very limited and this was great blow to German economy. In 3rd September 1950 peace treaty was signed in Shanghai, only confirming gains and loses of the war. Japanese gained all German Pacific islands including German New Guinea and Dutch Indonesia. However, Germans were allowed to keep North Borneo, since Germans successfuly defended this possession trough entire war, despite Japanese occupation of entire Indonesia. Japanese established Indonesian Confederation, new client state in the lands of former Dutch Indonesia and German New Guinea.
Time showed that German influence in East Asia would vanish without peace treaty. In 1951, Changsha Revolution shocked AlgOstAsien GmbH. Chinese had enough of ruthless exploitation of German companies and wave of revolution couldn't be halted by security forces. Germany, exhausted from war with Japan, made simple decision: AlgOstAsien GmbH was established in remaining German possessions in Indochina and Malasya. Republican revolutionary armies were strong enough to overthrow pro-German regime in Eastern Central China, but not strong enough to advance into Qing possessions and Southern China, which was still under German control. Germans didn't keep any possessions under direct control in Asia, but preseved their presence via semi-colonial corporation(all remaining German possessions were joined under AlgOstAsien GmbH) and trough loyal Qing Empire.
Qing Empire which had to side with Germany during Japanese invasion(Japanese invaded Imperial China also) stayed loyal German ally. Slowly Pu Yi managed to restore part of the old imperial glory. Crazy Baron Sternberg canceled his plans for domination of Asia since he couldn't get Tibetan support. Being aware of unpredictable situation in Asia, Tibet was more cautios and rather chosed more reliable side. Tibet became part of Chinese Empire again, but Dalai Lama stayed supreme religious ruler and great political authority. Tibet also preserved all cultural, religious and national rights, and broad autonomy granted by Chinese Emperor. Ma Clique soon followed Tibet and Sinkiang was again incorporated into Qing Empire. Ma family warlords sold their independence well, since they managed to achieve high positions in Empire. In 1955 cultist state of Shanqing Tiangue was finally crushed by Qing forces, ending threat of theocratic revolutionaries that preached destruction of Qing Empire and establishment of ''New Heavenly China''. In same year Yunnan Clique also accepted imperial authority, off course for price of several concesions in Empire. Those five years since the end of war in Asia were quite successful for Pu Yi, but China was still far from being united. It was always good to keep Germans near, but new Republic of China was great frustration for Pu Yi. He always wished to destroy Chinese Republic, but his wish was never granted.
Australasian Confederation which was born after unification of Australia and New Zealand after the Great War, survived chaos in Asia and stayed loyal member of Entente until modern day. Australasian Confederation also controls Fiji and some surrounding islands, and Port Moresby in New Guinea.