Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

This paper studies equilibrium determinacy in a growing New Keynesian economy in which fiscal policy targets the face value debt-to-GDP ratio and the government issues long-maturity nominal debt. Because the monitored debt stock is insensitive to market valuation while issuance costs depend on bond prices, expectations-driven movements in long-bond prices induce fiscal adjustment that feeds back to capital accumulation and inflation. The determinacy region is bounded above by an admissible policy constraint. Local determinacy requires the inflation response to lie above a maturity-based cutoff and below this admissible upper bound, which can be close to one. A two-instrument extension with an ultra short bond shows how rollover exposure and portfolio shares shift both bounds. Numerical exercises show that determinacy may require an inflation coefficient only slightly above one together with a sizable output-gap response, and that longer maturity can tighten the determinate set relative to the flexible price benchmark.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

This paper studies child allowances as coordination devices in an overlapping generations economy with balanced budget family transfers, pay-as-you-go pensions, and endogenous child quality investment. Discrete fertility yields decline, replacement, and growth demographic regimes. In the benchmark economy with inelastic labor supply, the model delivers two closed form fertility thresholds and can sustain one, two, or three self-confirming steady states under a common permanent allowance system. Low-fertility regimes can remain privately self-confirming even when defensive education per child makes them socially costly. I then endogenize labor supply so allowance finance feeds back into the contemporaneous tax base. In that richer environment, the threshold logic survives, but the boundaries become implicit on the admissible set. The numerical exercise confirms decline-replacement coexistence and shows that a temporary allowance pulse need not trigger regime switching once payroll finance distorts the tax base.

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

This paper constructs a comprehensive dataset of Japanese equity total returns, real short-term interest rates, and inflation from 1924 to 2024 and studies how financial market efficiency evolves with economic development. Using a GLS-based time-varying VAR, we estimate a joint degree of market inefficiency that captures return predictability and show that efficiency improves over the long run but temporarily deteriorates around major macro-financial regime changes. To interpret these medium-run episodes, we build a monetary endogenous growth model with financial intermediation and borrowing constraints. A relaxation of financial constraints shifts the balanced growth path and slows convergence, generating transitional dynamics that make equity returns more predictable. We then generate pseudo data from the model, add noise, and apply the same time-varying VAR procedure; the estimated inefficiency measure rises during the transition and fades as the economy approaches the new steady state.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

This paper studies equilibrium determinacy under an interest rate rule when fiscal policy is governed by a face-value debt targeting rule and the government issues long-maturity nominal debt. Bond prices react to expected interest rates, while the monitored debt ratio is insensitive to market valuation. This mismatch creates a bond price channel: shifts in inflation expectations move bond prices, change issuance costs, and trigger fiscal adjustment that feeds back to capital accumulation and inflation. I characterize equilibrium determinacy by a maturity-based cutoff for the inflation response in the policy rule. Longer maturity and a higher long-bond share relax the cutoff, whereas short instruments can require very aggressive monetary policy feedback.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

This paper studies how debt rollover and government debt maturity shape the risk-free term structure in a stochastic overlapping generations economy. The government rolls over a stationary portfolio of non-contingent bonds and rebates the resulting net cash flows to households, splitting them between young and old cohorts. Because this split changes marginal utilities across cohorts, it endogenizes the one-period stochastic discount factor that prices every maturity. I characterize equilibrium as a fixed point in bond prices and provide conditions for existence and uniqueness of the equilibrium price system. The analysis describes which state-contingent rollover revenues can be generated through maturity choice and gives an exact decomposition of rollover gains into growth-related discounting, expected bondprice changes, and risk compensation (term premia). In a two-state log utility case, changing transfer incidence reverses yield curve slopes across states. Numerical exercises show sizable movements in yields and term premia with modest changes in intergenerational consumption shares.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

This paper examines how member selection and the timing of finalizing committee size shape information aggregation under conformity and heterogeneous biased priors. I model committee voting as a beauty contest game and show that the monotonicity result of the Condorcet Jury Theorem can fail. In a static design that fixes size ex ante, fixed-proportion sampling tends to amplify majority bias through the average action, often yielding a finite optimum, whereas i.i.d. sampling partially preserves monotonicity via composition averaging. The main results characterize the optimal dynamic design as an optimal stopping problem: potential members are added sequentially, and the designer stops based on the observed composition. In a two-type model with symmetric prior biases, I show that the optimal expected loss is monotone in a degree of imbalance of committee composition, and optimal stopping is governed by a threshold-type policy. Simulations illustrate that the optimal stopping-size distribution can differ substantially from the static optimum.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

We develop a shadow-value interpretation of the finite-horizon Brock–Mirman model and use it to obtain an explicit, time-varying closed-form solution. Viewing one unit of current output as a shadow price yields a simple linear relation over time and a short geometric adjustment: as the horizon shortens, the saving share falls while the consumption share rises. We also show that the closed form survives under proportional taxes: return- and investment- side wedges operate through the effective return and thus govern adjustment speed, whereas a pure consumption tax shifts levels only.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

This study found that the grading experience facilitated the information feedback effect of rank information on university students. Except for fairly high-performing students, participants reacted to the rank information only after receiving a grade evaluation. Rank information feedback had a negative effect on students' subsequent performances. These results suggest that the grading experience makes the rank information actionable.

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Using a general equilibrium model of a pure exchange economy with multiple bonds of different maturities, I design an infinite rollover scheme independent of the condition that the economic growth rate exceeds the interest rate, the so-called r ≤ g condition. While the r ≤ g condition is (not only a sufficient but also a necessary) condition for infinite rollover in an economy with only a single maturity bond, this is not the case in an economy with mul- tiple bonds of different maturities: If term structures of interest rates exist and significantly change according to economic states, there exists a state-invariant portfolio to carry out infinite rollover. I apply the infinite rollover scheme to a two-state model with fiscal policy and show that the fiscal stimulus under deficit financing is sustainable regardless of the r ≤ g condition.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

This paper analyzes the optimal combination of taxation and auditing in a growing economy with public capital accumulation and tax evasion. Unlike existing studies that treat audit expenditures exogenously, we consider optimal policies that incorporate long-run growth as well as the relationship between audit expenditures and the efficiency of public capital production. When the efficiency of public capital production is high, the relationship between audit expenditures and optimal tax rates is even qualitatively different from existing models, with a positive relationship between the two. Meanwhile, the high optimal tax rate of over 40% suggested by existing studies on tax evasion and optimal taxation in growing economies is also supported by the present model calibrated to developed economies.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

We examine welfare losses from corporate income tax competition using a two-country R&D-based growth model with international knowledge spillover that incorporates myopic households and policymakers' limited terms of office. Policymakers who consider myopic household welfare, due to their finite planning horizon, choose a higher corporate income tax rate through the tax competition to increase short-term wages rather than long-term growth. When the policymakers' planning horizon is about the length of time that real politicians serve, this effect is quantitatively large, and the corporate income tax rate in the Nash equilibrium is well above the social optimum. The welfare losses, measured in terms of the household consumption lost due to tax competition, reach several percent in typical cases, an order of magnitude larger than in the previous study, which reports smaller values of 0.11% to 0.28% for the corresponding parameter set.

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Authorship：Last author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

We analyze the welfare consequences of global corporate income tax competition, using a two-country model of endogenous growth with international knowledge spillovers. Although the Nash equilibrium tax rate can be excessively high or low according to the degree of spillover, this does not lead to significant welfare losses. The key to this outcome is that corporate income tax competition for growth maximization, which we consider hypothetically, attains the maximum growth rate, despite complex externalities and strategic interactions.

DOI： 10.1016/j.euroecorev.2024.104723

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

Through a comparative dynamic analysis, we argue that the reality of public debt issuance, which responds flexibly to business cycles in contrast to the EU’s institutionally prescribed fiscal discipline, may contribute to macroeconomic stabilization. Through a simple econometric analysis, we find that the real operations of public debt management in European countries with excessive public debt are rather consistent with such flexible rules, even though the official EU fiscal discipline requires that the debt-to-GDP ratio be kept monotonically close to its long-run target. Using a small open economy model of endogenous growth, we demonstrate that the flexible debt policy rule serves to eliminate sunspot fluctuations due to equilibrium indeterminacy that occurs under official fiscal discipline. We also find that the flexible rule can lead to endogenous business cycles that depend only on economic fundamentals under equilibrium determinacy.

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Authorship：Corresponding author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Cambridge University Press  

We explore how tax evasion by firms affects the growth- and welfare-maximizing rates of corporate income tax (CIT) in an endogenous growth model with productive public service. We show that the negative effect of CIT on growth is mitigated in the presence of tax evasion. This increases the benefit of raising the CIT rate for public service provision. Thus, in contrast to Barro (1990), the optimal tax rate is higher than the output elasticity of public service. Through numerical exercises, we demonstrate that the role of tax evasion by firms is quantitatively significant.

DOI： 10.1017/S1365100521000638

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：Wiley-Blackwell  

Using an asset pricing model of a multi-sector production economy with pandemic disasters, we explain the average stock price boom and significant cross-sectional variation of stock returns in the US and Japan during the COVID-19 pandemic recession. Two features of the pandemic, ambiguity and sector-specific shocks, are crucial determinants of the unusual asset price dynamics. Extending the model, we analyze the welfare effects of lockdown policies during pandemics for heterogeneous households and obtain the following results. Enforcing a lockdown improves the welfare of the asset-holders and the household working in the sector with positive sector-specific shocks. A Pareto optimal lockdown policy controls the tightness of the lockdown so as to maximize the welfare of the household working in the sector with negative sector- specific shocks.

DOI： 10.1111/jpet.12591

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Language：English  

Using a simple model of a coordination game, this paper explores how the information use of individuals affects an optimal committee size. Although enlarging the committee promotes information aggregation, it also stimulates the members’ coordination motive and distorts their voting behavior through higher-order beliefs. On the determination of a finite optimal committee size, the direction and degree of strategic interactions matter. When the strategic complementarity among members is strong, a finite optimal committee size exists. In contrast, it does not exist under strategic substitution. This mechanism is applied to the design of monetary policy committees in a New Keynesian model in which a committee conducts monetary policy under imperfect information.

DOI： 10.3390/math9101098

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Public Library of Science  

Previous studies have revealed the role of relative performance information feedback on providing agent incentives under a relative rewarding scheme through laboratory experiments. This study examines the impact of relative performance information feedback of students’ performance on their examination score under the relative grading scheme in an actual educational environment. Conducting a randomized controlled trial in a compulsory subject at a Japanese university, we show that the relative performance information feedback has a significantly positive impact on the students’ examination score on average, but that the average positive impact is derived by the improvement of low-performing students.

DOI： 10.1371/journal.pone.0231548

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AccessEcon  

This study re-examines the optimal delegation problem of monetary policy under preference uncertainty of the central banker. Liberal central bankers are desirable when uncertainty is strong, which is emphasized when the slope of the Phillips curve is flatter, as some empirical works report. However, appointing conservative central bankers is optimal with standard parameter values when monetary policies are conducted by committees, as in most actual economies.

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Authorship：Lead author,　Corresponding author   Language：English   Publishing type：Research paper (scientific journal)  

DOI： 10.1111/jpet.12197

Web of Science

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Authorship：Lead author   Language：English  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AccessEcon  

This paper analyzes the relationship between the optimal weight on output gap in the central bank's loss function and the degree of inertia in a hybrid version of New Keynesian model with a pure discretionary inflation targeting. I show that under endogenous persistence of inflation dynamics, even in discretionary monetary policy regime, a Rogoff's (1985) conservative central banker does not necessarily improve social welfare.

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Authorship：Lead author   Language：English  

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Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：日本評論社  

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Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：日本評論社  

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Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：日本評論社  

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Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：日本評論社  

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Publishing type：Article, review, commentary, editorial, etc. (trade magazine, newspaper, online media)   Publisher：東洋経済新報社  

全世界的に法人税率が低下傾向にある背景を租税競争の観点から説明し、租税競争の厚生的評価に関する学術研究（自著）の分析結果を一般向けに紹介した。ヒト・モノ・カネ・情報が自由に国境を越える現代では、租税競争による経済効果は知識の伝播によって中和されるので世界的な経済厚生は低下しない可能性があることを述べてい

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Language：English   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Oral presentation (general)  

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Language：English   Presentation type：Oral presentation (general)  

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Language：Japanese   Presentation type：Oral presentation (invited, special)  

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