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Mutual East Asian Cooperation Union

(South China (Taiwan) flag by u/Hong-Kong-Pianist,
Karafuto flag by u/RiketVs [colors reversed])
Events leading up to the formation of the Mutual East Asian Cooperation Union
1560 - After the internal "War of Lost Songs," Hatsunia engages in a policy of non-interference - no isolation, but no expansion either. Exposure to foreign cultures reduces xenophobia (but not completely, there are still struggles for civil rights later on).
1868 - Creation of the Moeji Constitution; "half-and-half westernization" (emulation of western democratic systems but not blatant colonialist policies; natural resources are traded for, not colonized)
1884, 1899 - Hatsunia acquires the autonomous prefectures of Micronesia (purchased from Spain). This is the only overseas territorial acquisition of Hatsunia.
1906 - Hatsunia and Korea fight against Russia, leading to the creation of the joint administrative zone (later republic) of Karafuto. Hatsunia is friendly towards Korea, as aggression would push it to
side with Russia and become a "dagger pointed at the heart of Hatsunia."
1939 - The fascist Blue Shirts Society manages to take over China, which joins the Axis Powers in WWII due to
Sino-German cooperation. Hatsunia joins the Allied Powers.
1941 - Honolulu Pact formed between Hatsunia and the United States.
1945 - China is defeated and split into the communist North China and the capitalist South China.
1967 - Hatsunia and other East and Southeast Asian countries form the Mutual East Asian Cooperation Union. A yearly cultural expo is held.
The main difference between the Mutual East Asian Cooperation Union and ASEAN in our universe is that there is more political/economic integration (but not as much as the EU) and human rights and democracy are more enforced.
[OOC Disclaimer: Hatsunia is not about pretending "Japan did nothing wrong" (yes it did), this is just a hypothetical "what if a country like Japan had been nicer" scenario.]

(Edited from this image)