Prior to his faculty position, he worked as a research fellow in National Centre for Text Mining (NaCTeM) (in 2005) and as a post-doctoral researcher in University of Tokyo (in 2007-2011). He obtained his PhD from Graduate School of Information Science and Technology, University of Tokyo in 2007. He has served as a technical consultant in SmartNews Inc. since 2013. He is also a visiting research scholar of the Artificial Intelligence Research Center (AIRC), National Institute of Advanced Industrial Science and Technology (AIST). His research interests include natural language processing, text mining, and machine learning. He is also known as a developer open-source software toolkits including: CRFSuite (a fast implementation of Conditional Random Fields), SimString (an implementation for approximate string matching), and libLBFGS (a C library of L-BFGS).