According to NationMaster.com, Japan has the lowest tax to GDP in the western world with a "Total taxation as a percentage of GDP" of 27.1 % of GDP" compared to other countries, for example: Australia 31.5%, USA 29.6%, UK 37.4% and Sweden 54.2%.
Source: NationMaster.com
Based on OECD Revenue statistics
http://www.nationmaster.com/graph-B/
tax_tot_tax_as_of_gdp-taxation-total-as-of-gdp#source
Further reading:
Book - The Japanese Tax System
Learn more about travel in Japan at Motorcycle Japan