My research interests have been in analytical theory of the firm, general equilibrium analysis, game theory, and fixed-point theory. I would like to understand the simultaneous workings of the firm-specific resource allocation mechanism and the (neoclassical) market mechanism. I formulate the former mechanism as the generalized strategic game in which decision-makers can coordinate their strategies.

My early results from this economic investigation include the establishment of an equilibrium existence theorem, where the new equilibrium concept is a solution to simultaneous workings of the firm-specific resource allocation mechanism and the market mechanism. I later extended this line of research to also cover production theory with increasing returns to scale and theory of comparative economic systems.

To solve these economic questions, I pioneered research in cooperative extensions of the noncooperative game, a basic area which serves as a game-theoretical foundation of economic analysis, and looked into the underlying fixed-point theory. Among my early results from the research in cooperative extensions is the establishment of a social coalitional equilibrium existence theorem, which includes Nash's equilibrium existence theorem (the Nash equilibrium is a typical noncooperative solution concept), Scarf's core nonemptiness theorem (the core is a typical descriptive cooperative solution concept) and Arrow-Debreu-McKenzie's competitive equilibrium existence theorem as special cases.

Recently, I have been working on cooperative extensions of the Bayesian game, which is also Bayesian extensions of a cooperative extension of the noncooperative game. One of my notable results in this area is an explanation of how private information is revealed to the public.

Currently I am involved in further research on information revelation in (generalized) cooperative games with incomplete information.