A decline in real interest rates can be expected to stimulate private demand such as business fixed investment, private consumption, and housing investment. Such an increase in private demand in turn reduces the output gap, that is, the amount of slack in the economy as a whole, thereby putting upward pressure on prices.
The figures for "Before QQE" and "After QQE" show the annualized growth rates of employees from 2008/Q1 to 2013/Q1 and those from 2013/Q1 to 2018/Q4, respectively. Source: Ministry of Internal Affairs and Communications, "Labour Force Survey."