The effects of the 1990s reforms to the electoral system of Japan's House of Representatives have been among the most frequently discussed topics in political science research on the country. These reforms saw the replacement of a hitherto single nontransferable vote (SNTV) system by a mixed-member majoritarian (MMM) system with a strong Single Member District (SMD) and a weaker Proportional Representation (PR) component. Many studies have suggested that the reforms may have had significant impact on the strategies of political parties. Generally, SMD systems have been widely thought to favor larger parties, while PR systems are more beneficial to small and medium-sized parties. On the content side, larger parties seeking control of the government would try to win the support of large numbers of floating voters by campaigning on universal/programmatic policy appeals, as opposed to particularistic interests. In contrast, smaller parties would cater towards their core supporters’ preferences. Previous studies have noted that the old SNTV system in Japan had produced results similar to PR systems (Reed 2003). Japan's electoral reform may have thus changed the strategy of large parties, which would need to win more seats in the SMDs to gain (or hold onto) power, while smaller parties have continued to try and win seats via the PR tier. Therefore, the reform provides valuable research material in so far as we can simultaneously observe different effects by the SMD and the PR systems on parties of different sizes.

In many countries, constitutional amendments require the direct approval of voters, but the consequences of fundamental changes to the powers and operations of the state are difficult to anticipate. The referendums literature suggests that citizens weigh their prior beliefs about the merits of proposals against the heuristic provided by the partisanship of the proposer, but the relative salience of these factors across constitutional issue areas remains underexplored. This paper examines the determinants of citizen preferences on 12 diverse constitutional issues, based on a novel survey experiment in Japan. We show that support for amendments is greater when its proposer is described as non-partisan. However, constitutional ideology moderates this effect. Those who prefer idealistic constitutions that elevate national traditions tend to value proposals that expand government powers, compared to those who prefer pragmatic constitutions that constrain government authority. These results highlight the significance of constitutional beliefs that are independent of partisanship.

In this article I examine changes in the election manifestos of Japan's Liberal Democratic Party. While the existing literature agrees that the LDP's policy platform has changed considerably since the introduction of the new election system in the 1990s, their analysis focuses on material policies such as pork barrel and welfare. Postmaterialist policies such as environmental protection have hardly been discussed, even though they have been relevant since pollution swept progressive mayors into power in the 1960s. I examine election platforms from 1956 through 2013, and argue that the LDP has carefully adjusted its policy mix by putting a greater emphasis on postmaterialist policies. My analysis also shows that while electoral reform has had an impact on the policy balance between postmaterialist and materialist policies as well as clientelist and programmatic policies, these changes are not linear, but vary from decade to decade.