... well, Japanese national debt percentage of GDP is over 200%! This is one of the mysterious Japanese macroeconomic factors.
One of the reason is that approximately 90% or more of Japanese national bond holders are Japanese nationals. This is why the government can keep these bond holders even with a substantially low interest rate. The hidden cost of this policy is incurred upon Japanese economy because the government is hardly able to raise the interest rate even during the inflationary period.
Furthermore, the value of Japanese national bond is so stable that the capital loss risk is low. Because there is still a regular coupon payment (the income gain) with the low capital loss risk at the moment, the majority private banks in Japan keep holding the national bond as the secure asset. The majority Japanese citizens are so risk-averse that they hardly split their saving to private investment: Then, the private bank simply shift their saving account money to the national bond purchase. Although the coupon payment is not so high, the risk premium is still lower than any private bond for the moment. Their risk-averse personality is one of the strong drive of stabilising the national bond price.
Nevertheless, it is sceptical to assume this mechanism can keep going on. Japanese economy has been stagnated for multiple decades since the last economic bubble burst in 1990s. Nowadays, Japanese economic indices show that Japanese economic strength is even weaker than before. In addition, the entire macroeconomic strength will keep going down due to the ongoing ageing population combined with the constant substantial population decline.
