Profile Information
- Affiliation
- Professor, Department of Political Studies, Faculty of Law, Gakushuin University
- Degree
- Ph.D. in political science(University of Tokyo)
- J-GLOBAL ID
- 201601019304629416
- researchmap Member ID
- B000256475
- External link
Research Interests
4Research Areas
1Research History
7-
Apr, 2026 - Present
-
Apr, 2026 - Present
-
Apr, 2023 - Present
-
Apr, 2022 - Mar, 2023
Education
4-
Apr, 2008 - Mar, 2011
-
Apr, 2006 - Mar, 2008
Committee Memberships
7-
Jun, 2025 - Dec, 2025
-
May, 2024 - May, 2025
-
May, 2018 - May, 2024
-
Aug, 2023 - Jan, 2024
-
Aug, 2022 - Jan, 2023
Awards
6Papers
35-
Journal of Elections, Public Opinion and Parties, Aug 7, 2026 Peer-reviewedPrevious studies examining the demand side of democratic backsliding have focussed on partisan motivation as the leading cause of voters' acceptance of executive aggrandizement. A recent study by Grossman et al. [2022. “The Majoritarian Threat to Liberal Democracy.” Journal of Experimental Political Science 9 (1): 36–45] argues that a substantial proportion of voters grant popularly elected politicians considerable latitude and that such a majoritarian understanding of democracy is the driving force behind democratic erosion. This paper compares these two perspectives using an online public opinion survey conducted in Japan, one of the least politically polarized democracies worldwide, comprising both an observational component and a preregistered survey experiment. Analysis of the survey data reveals that respondents were more inclined to support executive power grabs when these were framed as aligning with citizens' views in policy formulation. In addition, we estimated that a substantial subset of respondents was classifiable as “election supremacists,” meaning that they supported such power grabs and regarded them as democratic regardless of the partisanship of the chief executive. This paper contributes to the literature by presenting a new case wherein the public's majoritarian understanding of democracy may pose a threat to democratic politics.
-
Public Opinion Quarterly, Jun 24, 2026 Peer-reviewedComparative public opinion surveys, including the Comparative Study of Electoral Systems (CSES), often rely on identical labels and question items to measure respondents’ symbolic and operational ideology across countries. However, it remains unclear whether common symbolic measures of ideology carry the same meaning across contexts, or whether the issue items used to construct common operational measures are equally relevant in national settings. To address these concerns, we compare symbolic and operational ideology as measured using common cross-national items and country-specific items. We conducted public opinion surveys before and after national elections in seven Asian and Western countries. Our analyses reveal that (i) country-specific measures of ideology are generally more stable over time than common measures, (ii) country-specific symbolic and operational ideology are more strongly associated with each other than their common counterparts, (iii) respondents tend to have a greater understanding of country-specific ideological labels than common ones, (iv) country-specific measures are generally more predictive of vote choice in elections, and (v) ideological extremity, as measured by these two types of indicators, shows different correlations with respondents’ attitudes toward democratic values. These findings suggest that researchers should use country-specific measures of ideology in comparative public opinion research.
-
Political Science Research and Methods, May 29, 2026 Peer-reviewedDoes permitting voters to select multiple candidates in majoritarian elections increase diversity among those elected? While majoritarian systems typically use single-vote ballots, research suggests that allowing multiple selections may increase the representation of women and racial minorities. However, empirical evidence regarding actual voter behavior remains limited. To address this gap, we conducted a survey experiment that varied the number of selectable candidates from one to three in multimember local elections. The results revealed that, under the multiple-vote condition, respondents were more likely to alternate by gender, particularly in their second- and third-ranked choices, supporting the theory that multiple voting fosters more diverse representation. Nevertheless, men often emerged as the first-ranked choice, giving them an overall advantage at the aggregate level.
-
Public Opinion Quarterly, Apr 25, 2026 Peer-reviewedDoes permitting voters to select multiple candidates in majoritarian elections increase diversity among those elected? While majoritarian systems typically use single-vote ballots, research suggests that allowing for multiple selections may increase the representation of women and racial minorities. However, empirical evidence regarding actual voter behavior remains limited. To address this gap, we conducted a survey experiment that varied the number of selectable candidates from one to three in multi-member local elections. The results revealed that, under the multiple-vote condition, respondents were more likely to alternate by gender, particularly in their second- and third-ranked choices, supporting the theory that multiple voting fosters more diverse representation. Nevertheless, men often emerged as the first-ranked choice, giving them an overall advantage at the aggregate level.
-
Social Science Japan Journal, 29(1) jyag001, Mar, 2026 Peer-reviewedLast authorCorresponding authorUnderstanding the ideological positions of political parties is crucial for empirically testing various theories in political science. In Japan, some studies have assessed each party’s policy outlook through electoral platforms, candidate surveys, or expert surveys, with most studies focusing on the past thirty years. However, limited efforts have comprehensively and longitudinally quantified the conflicts between political parties. Although previous studies have used election-related data to reveal interparty conflicts during elections, interparty conflicts between elections remain unclear. This study determines the stance of Japanese political parties during parliamentary debates. We collected text data from committee speeches from the Diet Proceedings Database from 1959 to 2019 and conducted a quantitative text analysis. By applying the Wordshoal method, we first estimated political party positions on specific policy topics in the House of Representatives and the House of Councillors. Then, we aggregated these policy-specific positions yearly via dynamic factor analysis. Consequently, we succeeded in discerning the axis of conflict in Japanese parliamentary debates and evaluated the longitudinal one-dimensional ideal points for political parties. Additionally, we visualized the changes in each party’s ideological position, identified controversial topics, and explored how these topics changed over time, providing new insights into the study of Japanese politics.
Misc.
24-
RIETI Discussion Paper Series, 25-E-047, May, 2025
-
CSRDA Discussion Paper Series, 109, Nov, 2024
-
CSRDA Discussion Paper Series, 105, Nov, 2024
-
2022 289-294, Dec 2, 2022 Peer-reviewedA text analysis was applied to the election manifestos. Two kinds of clustering methods were utilized and compared: microclustering that extracted dense substructures from the network constructed based on the similarity of the documents, and the LDA model, which is a kind of topic model. The microclustering gave many clusters that were easier to understand their topics, especially for the party of candidates. Furthermore, regression analysis was applied to the obtained clusters, and the tendency of candidates with personal-oriented was elucidated. The results correspond to previous studies, such as the change of the electoral rule and the characteristics of each political party, without any manual topic interpretation process as in the previous studies.
Books and Other Publications
3Presentations
70-
2026 International Symposium on Quantitative Political Science: Methods and Applications, May 7, 2026 Invited
-
シンポジウム「デジタル時代の『公共』をめぐる法と政治の相互作用」, Feb 24, 2026 Invited
-
2026 Elite and Public Views of East Asian Security Workshop, Jan 23, 2026 Invited
-
2025 International Conference on Asian Election Studies, Oct 25, 2025 Invited
-
日本政治学会2025年度研究大会, Oct 12, 2025, 日本政治学会
-
The 121st Annual Meeting of the American Political Science Association, Sep 11, 2025, American Political Science Association
-
The 28th International Political Science Association World Congress of Political Science, Jul 14, 2025, International Political Science Association
-
The 28th International Political Science Association World Congress of Political Science, Jul 14, 2025, International Political Science Association
-
Program on U.S.-Japan Relations Associates' Panel, “New Frontiers in Japanese Public Opinion Research”, Feb 3, 2025, Program on U.S.-Japan Relations, Weatherhead Center for International Relations, Harvard University
-
計量・数理政治学会2025年冬季集会, Jan 5, 2025, 計量・数理政治学会
-
The 120th Annual Meeting of the American Political Science Association, Sep 6, 2024, American Political Science Association
-
日本選挙学会2024年度研究会, May 19, 2024, 日本選挙学会
-
計量・数理政治研究会2023年夏季集会, Jun 24, 2023, 計量・数理政治研究会
-
日本選挙学会2023年度研究会, May 21, 2023, 日本選挙学会
-
The 79th Annual Midwest Political Science Association Conference, Apr 9, 2022, Midwest Political Science Association
-
日本政治学会2021年度研究大会, Sep 26, 2021, 日本政治学会 Invited
-
May 9, 2021 Invited
-
東大社研政治学オンラインワークショップ, Jun 11, 2020 Invited
-
計量・数理政治研究会第3回冬季研究集会「計量・数理政治学のフロンティア」, Jan 5, 2020, 計量・数理政治研究会
-
戦前戦後・比較政治史研究/現代政治過程研究フォーラム2019年度春季研究会, May 18, 2019, 戦前戦後・比較政治史研究/現代政治過程研究フォーラム
-
Asian Electoral Studies Conference 2018, Oct 27, 2018 Invited
-
ISS Political Science Workshop 1, Jun 22, 2018 Invited
-
国際研究集会「計量・数理政治学のフロンティア」, Jan 9, 2018
Teaching Experience
13-
Apr, 2026 - PresentContemporary Japanese Politics (The University of Tokyo)
-
Apr, 2026 - PresentPolitical Process (Keio University)
-
Apr, 2025 - PresentQuantitative Analysis of Politics (Gakushuin University)
-
Apr, 2019 - PresentPolitical Process of Japan (Gakushuin University)
-
Apr, 2016 - PresentStatistical Analysis (Gakushuin University)
Professional Memberships
5-
2021 - Present
-
2021 - Present
-
2021 - Present
-
2013 - Present
-
2013 - Present
Research Projects
19-
Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2025 - Mar, 2030
-
Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Jun, 2025 - Mar, 2029
-
Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Sep, 2023 - Mar, 2029
-
Topic-Setting Program to Advance Cutting-Edge Humanities and Social Sciences Research, Japan Society for the Promotion of Science, Jul, 2023 - Mar, 2029
-
科学研究費助成事業, 日本学術振興会, Apr, 2024 - Mar, 2028