First Author:   Tetsuo Yamamori Graduate School of Economics, University of Tokyo ee27004@mail.ecc.u-tokyo.ac.jp   3-26-20-405 Raionzu-manshon-Nishidai-dai2 Hasune Itabashi-ku Tokyo, 174-0046, Japan   81-3-5970-0632(Phone) 81-3-5970-0632(Fax) Second Author: Satoru Takahashi Department of Economics, Harvard University stakahas@fas.harvard.edu   122 Aza-Ebisuyama Okuwajima Muya-cho Naruto, 772-0011, Japan   81-88-685-4561(Phone) 81-88-685-4561(Fax)