Associate professor at The University of Tokyo Research Center for Advanced Science and Technology. Born in Shunan, Yamaguchi in 1977. A case of birth asphyxia left him with cerebral palsy. Kumagaya requires the use of a wheelchair. After graduating from The University of Tokyo Faculty of Medicine, he worked at Chiba Nishi Hospital as a pediatrician and at Saitama Medical University Hospital as a pediatric cardiologist. After completing his Ph.D. at The University of Tokyo Graduate School of Medicine, he was appointed to be an associate professor at The University of Tokyo. The co-author of "Self Support for People with Developmental Disabilities (Hattatsu Shogai Tojisha Kenkyu)" [Igaku-Shoin], "How to Make Connection (Tsunagari no Saho)" [NHK Publishing], "Philosophy of Pain (Itami no Tetsugaku)" [Seidosha] and more.