Japan is actually the second biggest foreign holder of US debt. As of February 2014, Japan held 1.210 trillion of US debt while China held 1.272 trillion. http

Japan is actually the second biggest foreign holder of US debt. As of February 2014, Japan held 1.210 trillion of US debt while China held 1.272 trillion. http://www.treasury.gov/ticdata/Publish/mfh.txt http://www.treasury.gov/ticdata/Publish/mfh.txt I am having trouble finding historical data, but what I can find from the 90s indicates that Japan alternated for the top foreign US debt holder with the UK. I am not really sure what data to look for general Japanese foreign investment.