On December 14th, we will have an election of the House of Representatives. We do not have a big issue currently, so I guess the voter turnout is going to be low (around 59%). Dec 17 update: The actual turnout was 52.66%.
The following data show the trend of the voter turnout in Japanese House of Representatives elections. An election of the House of Representatives is held on an irregular base. The prime minister determines when we have the election. Intervals vary from one year to at most four years.
Figure : Trend of Voter Turnout in Japan House of Representatives Elections
Source is Ministry of Internal Affairs and Communications.