1. Department of Medicinal Chemistry, Faculty of Pharmaceutical Sciences, The University of Tokushima, CREST, Japan Science and Technology Corporation (JST), Shomachi, Tokushima 770-8505, Japan, Furuno Electric Co., Ltd., Nishinomiya 662-8580, Japan, and Single-Molecule Bioanalysis Laboratory, National Institute of Advanced Industrial Science and Technology (AIST), Hayashi-cho, Takamatsu 761-0395, Japan