system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How come during WWII it was America & China (Chiang Kai-shek) vs. Japan, but today's geopolitcal/financial rivals are set up much more along the lines of America & Japan vs. China

What did China do different after WWII and what did Japan do different after WWII to cause this shift in allegiances?
gpt
Japan was made into a more Western-style government and culture after WWII (Meiji was more on the industrial and economical side), and China got turned into a "evil capitalism" type Communist government, which still goes up to this day.

Chiang Kaishek's government is now Taiwan (they had to flee after they were defeated), and we're still pretty good with them (our claim that they are PRC is mostly for economical relations).

tl;dr Japan was obliterated and replaced with a (somewhat) new culture, China turned into Taiwan, China Mainland is called PRC and we're still really iffy about communism.