The Japanese yen has strengthened against the U.S. dollar over the last 20 years due to historic trends. The yen continues to strengthen due to Japan's large trade surplus, low domestic interest rates, and high demand from foreign investors seeking assets outside of the U.S. and Europe. Foreign demand for Japanese assets is driven by factors like foreign reserve diversification and Japan's stable monetary policy compared to other nations. This increased demand and decreased supply of yen on world markets causes the yen exchange rate to rise.