The People's Republic of Japan (PRJ) was established on the 20th January, 1966 when rebels in Japan succeeded in bringing Communism to Japan. Funded by the Warsaw Union and the PRC the rebels easily toppled the old government (taking American support of Japan with it though) and gained the support of the Warsaw Union and the Chinese. Japan's first Nuclear Bomb (ironically named "Fat Man II" to show their anger toward America) is successfully tested in the Pacific 500 miles off the coast of Wake Island. The US is understandably nervous about this. However, Japan is satisfied by this test and only arms nukes within its borders. Japan progressively becomes more of a puppet of the larger Communist states of the Warsaw Union and China then its own country. Propaganda from the two larger states fuels Japan's anger toward the US.
Second Korean Colony for Japan
The People's Republic of Korea is struggling to keep power over its people. Korea could absorb itself into either or both of its two neighbors but decides to be be re-annexed by Japan as a colony again. The Japanese accept the proposal and once The Warsaw Union and China approve, Korea is re-annexed.
Japanese founding of the Communist Committee
The Communist Committee is founded on January 20th, 1980 by Japan in response to the new Anglo Federation made by The US and primary English allies (Canada and the UK). China and The Warsaw Union both agree to the Committee which brings the 3 nations even closer together. The Committee is used to propose ideas for all nations and see if the other nations approve. It also links them militarily so that if one nation goes to war, all nations go to war. Do to the Korean people wanting membership Japan gives them a limited power membership, which basically means that Koreans have no say in anything but can observe what's going on in the Committee, effectively meaning they're just there to watch the other nations' proposals.