Main research topics :
- Contracting and Private Ordering
- Firm Boundaries and Internal Organization
- Formal Contracts, Relational Contracts, and the Threat-Point Effect (joint with Hodaka Morita). American Economic Journal: Microeconomics 7 (2015), 318-346.
- Complementarities among Authority, Accountability, and Monitoring: Evidence from Japanese Business Groups, Journal of the Japanese and International Economies 22 (2008): 207-228 (joint with Tatsuya Kikutani and Osamu Hayashida).
- Moral Hazard and Other-Regarding Preferences, Japanese Economic Review 55 (2004), 18-45.
- Cooperation in Hierarchical Organizations: An Incentive Perspective, Journal of Law, Economics, and Organization 8 (2) (1992), 321-45.
- Japanese Human Resource Management from the Viewpoint of Incentive Theory. Masahiko Aoki and Ronald Dore (eds.), The Japanese Firm: The Sources of Competitive Strength. Oxford University Press (1994), Chapter 9, 233-264.
- Incentives to Help in Multi-Agent Situations, Econometrica 59 (1991), 611-36.