The government of the time acquired its minting machinery from the former English Minting Authority in Hong Kong, and invited the engineers to Japan, asking them to issue silver coins of the same weight and quality as those used in Hong Kong.
They are affected by everything from international capital markets to land values, to government policy. In addition, VAT, local government policy, approvals processes, mezzanine finance rates, property price expectations, vacancy taxes and development levies all play a role. Some of these appear to be unintended consequences, others represent carefully considered trade-offs between policy goals.