This study examines the impact of donations made under the Hometown Tax Donation (HTD) system on local government expenditure. This study employs a mixed-methods approach that combines interview surveys with quantitative analysis, employing panel data analysis with instrumental variables. Hokkaido accounts for a relatively large share of the total HTD received when aggregated at the prefecture level. However, substantial variation exists among municipalities within Hokkaido in the amounts they receive. A key factor contributing to these differences is the availability of popular return gifts. Furthermore, reliance on return gifts poses challenges for municipalities in estimating their incoming HTD revenues, indicating that this revenue source is inherently unstable. This study shows that HTD revenue is probably accumulated in reserve funds while simultaneously increasing specific expenditures, such as welfare and sanitation costs. Thus, it offers new insights into the assessment of the HTD system.

　This study analyzes the determinants of invalid voting in Japanese House of Representatives elections from 1996 to 2021, using prefecture-level panel data. Invalid votes were classified into total invalid votes, blank and spoiled votes, and finer sub-categories to examine the effects of socio-economic factors and political variables, including turnout rate, LDP vote share, and vote margin. The analysis shows that in single-member districts, voter turnout generally exhibited a negative relationship with invalid vote rates, whereas the vote margin was positively associated with certain types of invalid votes. In contrast, virtually no significant relationship was observed between electoral competition and invalid voting in proportional representation blocks. Furthermore, even for the same explanatory variables, the direction and statistical significance of their effects varied across the different types of invalid votes. These findings demonstrate that invalid voting is not merely the result of voter error, but rather a complex voting behavior driven by distinct underlying mechanisms. In particular, from a public choice perspective, invalid voting can be interpreted as the outcome of a cost-benefit calculation made by voters between abstention and valid voting, suggesting that under conditions of weak electoral competition, the expected utility of casting a valid vote decreases, thereby increasing the likelihood that an invalid vote is chosen.