If I remember correctly, the reason on why the Japan's Central Bank imposed negative interest rates was to encourage its people to spend since most of them are saving their money either in the bank or on their respective houses. Due to this phenomenon, there lacks an inflow of cash in the economic machinery which makes the prices lower and cheaper BUT no one spends their money.

This would be a good opportunity if Bitcoin were to be introduced as an investment alternative since people would be spending and purchasing bitcoins, just like what they are currently doing. It would be a both win-win situation to their economy and to the price of bitcoin as well.