1. REVAST Co., Ltd., 2-68-12 Ikebukuro, Toshima-ku, Tokyo 171-0014, Japan
2. Faculty of Informatics, Gunma University, 1-5-1 Tenjin-cho, Kiryu, Gunma 376-8515, Japan
3. Graduate School of Science and Technology, Gunma University, 29-1 Hon-cho, Ota, Gunma 373-0057, Japan