Do public opinion have strong impact on political change in Japan?

The answer to this question is yes.

Traditionally, public opinion has not played major role in policy formation but it has increasingly strong influence since very recently.

First, uncommitted voter's support. Let’s take former TV personality Sonomanma Higashi’s case for example. He won the gubernatorial election in Miyazaki. His glass root campaign, with the slogan "Miyazaki must change and no bid-rigging attracted a large number of uncommitted voters. His high profile/fame might influence to bring people’s attention. But the fact also remains that they wanted to oppose against bid-rigging trend in Miyazaki. I believe that this is a good evidence to indicate public opinion’s impact.

Second, objection to LDP. The LDP experienced its crushing defeat in the July Upper House election. The LDP-led ruling coalition only managed to secure 47 seats, falling far short of the 64 needed to maintain control of the Upper House. The DPJ, the main opposition party, won a landslide victory to become the largest party in the House of Councilors. It is believed to be the result of blunder such as pension fiasco and improper remarks. For example, former Health Minister Hakuo Yanagisawa to exhort more women to get pregnant, dubbing them "birth-giving machines". The LDP has dominated Japanese politics for most of the post war period. Other parties simply haven’t had enough strength to win national elections. There is general tendency for parties in power for a long time to become arrogant, complacent and corrupt. But at last, public opinion has strong impact on policy making.

In conclusion, public opinion has increasingly had strong impact on political change.