The Dodge Line after World War II fixed the yen to dollar ratio at 360 JPY to 1 USD. This weaker yen played a large part in why Japan was able to recover so spectacularly after the war because, along with having a guided economy (i.e. the government was basically directing the large keiretsu what to focus on), the weaker currency meant that Japan could sell its goods for cheaper.
This is why Japan became so dominant in electronics and cars by the 70s and where a lot of the stuff about Japan being the future masters of the world (most realized in the cyberpunk genre) came from. They could export TVs and radios and cars for so cheap that they could be sold in, say, the US for cheaper than their American counterparts. The US did the whole Plaza Accord deal in 1985 specifically to counter Japan. The strengthened yen slowed down their export economy leading to recession which caused the Bank of Japan to start offering lower interest loans stimulate the economy so companies, now flush with cheap and easy cash, needed to spend this money on something and hey look, land seems like a really good investment and I think you can see where I'm going with this.
Both China and South Korea are copying what post-war Japan (and West Germany) was doing to a large extent (weak currencies to spur an export driven economy) and look where that's getting them.