Tetsuya Sakai is a professor and the head of the Department of Computer Science and Engineering, Waseda University, Japan. He is also a visiting professor at the National Institute of Informatics. He joined Toshiba in 1993 and obtained a Ph.D. from Waseda in 2000. From 2000 to 2001, he was supervised by the late Karen Sparck Jones at the Computer Laboratory, University of Cambridge, as a visiting researcher. In 2007, he joined NewsWatch, Inc. as the director of the Natural Language Processing Lab. In 2009, he joined Microsoft Research Asia. He joined the Waseda faculty in 2013. He is an editor-in-chief of the Information Retrieval Journal (Springer) and an associate editor of ACM TOIS. He received a Waseda University Teaching Award in 2014 and a Waseda University Presidential Teaching Award in 2016.