Achieving JPY appreciation vs. the USD would require a narrower interest rate gap between the US and Japan, which is partly dependent on Fed policy. 

The JPY's current weakness is a double-edged sword. While it has significantly fueled Japan's export growth and equity market performance, its weakness is adding to imported price pressures. To that end, the weak JPY may be a key consideration for the BoJ to tighten policy in the foreseeable future as it seeks to stabilise import prices and safeguard consumers’ purchasing power.