Masahiro Yamada (山田 昌弘, Yamada Masahiro; born November 30, 1957) is a Japanese sociologist known for coining popular sociological terms like parasite singles and gap-widening society (格差社会, kakusa shakai). A graduate of University of Tokyo, he now teaches at Tokyo Gakugei University as professor.
Source: “Masahiro Yamada (sociologist)”, English Wikipedia (CC BY-SA 4.0), excerpt
