Looking back at the saving-investment balance, excess saving in the household sector has narrowed, reflecting the aging population, while saving has been exceeding investment in the corporate sector since around the end of the 1990s.
This seems to be because a persistent decline in the number of firms has led to a reduction in investment in the corporate sector as a whole, and a decline in population has restrained investment through a decline in the expected growth rate. The natural rate of interest declined toward the mid-1990s and has not recovered from a low level since then.