1. NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Atsugi, Kanagawa, Japanmasa.sawayama@gmail.comhttp://www.kecl.ntt.co.jp/people/sawayama.masataka/
2. NTT Communication Science Laboratories, Nippon Telegraph and Telephone Corporation, Atsugi, Kanagawa, Japanshinyanishida@mac.comhttp://www.kecl.ntt.co.jp/people/nishida.shinya/
3. Department of Information Science, Toho University, Funabashi, Chiba, JapanUEI Research, DWANGO Co., Ltd., Tokyo, Japanshinya@is.sci.toho-u.ac.jphttp://www.cg.is.sci.toho-u.ac.jp/sensei.html