Sovereign debt level in Japan causes concern

Japan''s sovereign debt 'has reportedly reached a potentially explosive level. It is already widely known that Abe's rightwing government also faces many other accumulated and pretty messy economic challenges. Japan's economy has been in a state of stagnation for some 20 years, although it is still the third single largest ('in term of G.D.P) on earth. From 1960 to 1990, Japan''s economic model inspired admiration and emulation in many other countries, 'especially South Korea and China. In the 1980s, Japan's economic triumphalism also caused some panic reactions or not-so-pleasant feelings in the United States and Europe. What are the lessons to be learned now from the downturn of Japan ?