Japan's most profitable and sustainable industry is the financial sector.
Japan's heavily nationalized banking system contains wealth that has been accumulated from countries such as China, Philippines, and Korea (North and South) during WW II.

The Tokyo Stock Exchange is the third largest stock exchange in the world by market capitalization, as well as the 2nd largest stock market in Asia, with 2,292 listed companies.
The Nikkei 225 and the TOPIX are the two important stock market indexes of the Tokyo Stock Exchange.
The Tokyo Stock Exchange and the Osaka Stock Exchange, another major stock exchange in Japan, merged on 1 January 2013, creating one of the world's largest stock exchanges.
Other stock exchanges in Japan include the Nagoya Stock Exchange, Fukuoka Stock Exchange and Sapporo Securities Exchange.
Japan's most profitable and sustainable industry is the financial sector. Japan's heavily nationalized banking system contains wealth that has been accumulated from countries such as China, Philippines, and Korea (North and South) during WW II. 
The Tokyo Stock Exchange is the third largest stock exchange in the world by market capitalization, as well as the 2nd largest stock market in Asia, with 2,292 listed companies. The Nikkei 225 and the TOPIX are the two important stock market indexes of the Tokyo Stock Exchange. The Tokyo Stock Exchange and the Osaka Stock Exchange, another major stock exchange in Japan, merged on 1 January 2013, creating one of the world's largest stock exchanges. Other stock exchanges in Japan include the Nagoya Stock Exchange, Fukuoka Stock Exchange and Sapporo Securities Exchange.
Economy of Japan