Short answers, pulled from the story.
The first gold yen coins struck in 1870 were minted at the San Francisco Mint. This decision to produce currency abroad was driven by the urgent need to establish a unified monetary system following the collapse of the Tokugawa shogunate.
The Bank of Japan began operations on the 10th of October 1882. It was granted a monopoly on controlling the money supply to ensure that the state could manage the flow of currency and stabilize the economy.
The Allied occupation government fixed the value of the yen at 360 yen per US dollar on the 25th of April 1949. This fixed rate was maintained until 1971 when the United States abandoned the gold standard.
From its average of 239 yen per US dollar in 1985, the yen rose to a peak of 128 yen in 1988. This rapid appreciation made Japanese exports less competitive and damaged the industrial base.
The 1 yen coin is made out of 100 percent aluminum and can float on water if placed correctly. This unique feature has made it a favorite among collectors.
The first coins of the Reiwa era were minted in July 2019. The reverse side of all coins shows the year of mintage in the regnal year of the reigning emperor rather than Gregorian calendar years.