Matsui is Associate Professor at the Faculty of Life and Environmental Sciences, the University of Tsukuba, Japan. He received his Ph.D. from the University of British Columbia, Canada, in 2003, and taught in Canada until 2007. Since 2008, he has taught at the University of Tsukuba. As the principal researcher for Japanese government research grants, he has conducted researches on water rights, water ethics, water governance, Indigenous/traditional knowledge, Indigenous rights, biodiversity policies, and environmental dispute resolutions. He is the author of Native Peoples and Water Rights (Montreal: McGill-Queen’s University Press, 2009) and Culture and Sovereignty of Indigenous Peoples in North America (University of Tsukuba Press, 2013) as well as many academic journal publications. He has also contributed numerous articles to public magazines. He has served as the guest editor for two international journals, Water History (The Netherlands) and International Indigenous Policy Journal (Canada). In 2013, he was the Rachel Carson Fellow at the Ludwig-Maximilian University of Munich (LMU). He has more than thirteen years of experience as research consultant for law firms and Indigenous peoples’ organizations in Canada.

Since 2013, Matsui has served as the chair of the Sustainability Science, Technology, and Policy (SUSTEP) Program at the University of Tsukuba. This program encompasses both master’s and doctoral degrees and aims to foster global leaders. In this Program he has coordinated JICA-funded education activities for young government officials from 17 countries in Asia, Africa, and the Oceania. He teaches courses related to human/regional geography, environmental ethics/policies, and environmental history.