One factor that contributed to social mobility in Japan was the rapid economic growth between 1955 and 1985 with Japan's industrial structure changes. However, after the
bubble economy burst in 1990, Japan entered a period of development stagnation known as the
Lost Decade. Therefore, the occupational prestige, education levels, and assets among different social classes still existed and were not eliminated by industrialization. The trend of
class stratification first appeared in the 1980s, and the main manifestations included the stagnation of equalized distribution, the fixation of employment patterns, and the narrowing gap between occupations. Therefore, wages and salaries were no longer the main variables in the
economic stratification; instead, the difference in household assets became increasingly important in the economic stratification. During the bubble economy in the late 1980s, the huge wealth brought by the substantial appreciation of the
Japanese yen was invested in stocks, securities, and real estate. The difference between financial assets and land prices rapidly expanded. Assets replaced wage income and became the determining factor of people's economic status and consumption patterns. In 1980, Murakami Yasusuke put forward the concept of "The Age of New Middle Mass Politics", where the middle class was defined as "middle level of standard of living", "conservative ideology", and a sign of social stability. However, middle class was largely influenced and destabilized by the bubble economy burst in 1990, causing the instability of the whole society. ==Impact of public policy on social mobility==