Tsuyoshi Toshimitsu Kwansei Gakuin University   1-1-115 Uegahara Ichibanchyo, Nishinomiya Nishinomiya, 6628501 日本   ttsutomu@kwansei.ac.jp             JEL Areas: L1 : Market Structure, Firm Strategy, and Market Performance: General D4 : Market Structure and Pricing: General