Why is there no public debt crisis in Japan?

Many economists and investors are concerned about the level of public debt ratios in the United States and the euro zone. Yet Japan’s public debt ratio is considerably higher than that of the United States or the euro zone, and there is no public debt crisis in Japan. How can this be explained? The usual explanations for why Japan’s public debt ratio can be so high are: The fact that Japanese savers and investors have a preference for yen-denominated debt; yet we see that foreign bond holdings by Japanese savers have become significant; The fact that total debt (public and private, government, household and corporate) is not very high in Japan, public debt being the exception. In reality, Japan’s total debt ratio is very high; The fact that the private savings rate (of all economic agents apart from public authorities) is very high, in particular due to income distribution between wage earners and companies, which is very favourable to companies, which enables Japanese companies to have very high savings; The fact that since 2013, the low level of long-term interest rates (nominal and real) relative to the growth rate has made the very high public debt ratio sustainable. All things considered, the relevant explanations for why Japan can have a very high public debt ratio seem to be that Japan has a very high private savings rate, and that since 2013, Japan's long-term interest rate has been well below nominal growth. We can the refore see that public debt sustainability is ensured by : A high private savings rate in both the euro zone and Japan ; A high level of GDP growth relative to the long-term interest rate in the United States, the euro zone and Japan, but not by a high private savings rate in the United States.