A group of lawyers appealed to the Tokyo District Court that Japan's upcoming lower house general election will be unconstitutional. However, their case was rejected by the courts on November 21, 2012.
Prime Minister Yoshihiko Noda dissolved the lower house of the Japanese parliament on November 16, and set general elections for December 16. According to a group of lawyers, the value of one vote varies in constituencies and because of this vote value disparity, these planned elections are actually unconstitutional.
The map  [ja] explains the values per vote in different areas for the lower house under the single-seat constituency electoral system . Areas colored in red have less than half the value of one vote. This was calculated based on the number of voters  for each constituency, showing the disparity of one vote between less populated areas and more populated areas. According to the website of ippyo.org , a coalition formed to tackle this issue, the value per vote in Osaka district 1 is counted as 0.57 vote for the lower house election and 0.21 for the upper house election.
Last month, on October 17, the Supreme Court ruled  that the election of the upper house in 2010 which had a maximum disparity of 5 to 1 was unconstitutional. Also earlier in March 2011, the Supreme Court decided that the unequal representation of electoral districts in the 2009 election had been unconstitutional.
On November 15, electoral reform bills were passed [ja]  and a new revision was introduced to reduce the disparity of vote value in the upper house constituency. However, it is not clear how these reforms apply to the lower house elections.
The hashtag #ippyo  was used on Twitter to discuss the issues around the gap in the value of vote.
This time, Prime Minister Noda dissolved the parliament and set elections with constituencies being in an unconstitutional state. It is unlikely that this election will reflect the opinion of citizens. At first, we saw media coverage on this issue, but now they cover more on the election itself and hardly about the issue of this unconstitutional situation. I wonder how long this situation will continue. #ippyo
Twitter user watakenn3  comments that this problem is not new and has been around for a while:
In school, people learn about the electoral system just at face value to prepare for their exams. It is not recognized as a problem. The term “disparity between values of votes in different constituencies” has been in textbooks for more than 10 years and so I say roughly 60% of the population should be aware of it. But not much progress has been made.
Another user yusaku79  also wants Japan's generation gap to be addressed in the electoral system:
I want a new system to be implemented that addresses the gap of population by generation per vote.
If one vote's value is half of one vote, why can't I just cast 2 votes.
The general election poll date is expected to be December 16.