The Financial Times reports that Japan’s Financial Services Agency is considering how to treat PokéCoins, which by extension would affect other RMT currencies. It is not the case that Japan is considering making PokéCoins an official currency or anything like that, despite how I expect to see this reported elsewhere.
The issue the FSA is studying is whether PokeCoins and other virtual currencies that can be purchased in-game with actual cash should be legally classified as a prepayment system, and therefore come under the jurisdiction of Japan’s recently updated Payment Services Act.
I know almost nothing about Japanese finance law, but that would presumably mean treating the RMT currencies like pre-paid gift cards, your Steam wallet, etc. I do not know how that would affect the fact that most F2P games also give away small amounts of RMT currency. I do not know how that would create liability in terms of data losses and game changes that negatively affect your RMT currency. It explicitly could mean more paperwork for games with RMT currencies and possibly depositing real cash in a Japanese bank to cover some of the outstanding virtual currency, the way that a store might need to show deposits to cover pre-payments that might be withdrawn.
Hat tip to Marginal Revolution.