Professor at Kansai University. Hirai received his M.A. and Ph.D. from Kansai University. He worked as a curator at Hyogo Prefectural Museum of Modern Art, Kobe from 1988 to 2002, Hyogo prefectural Museum of Art from 2002 to 2006, The National Art Center, Tokyo from 2006 to 2012 and The National Museum of Modern Art, Kyoto from 2012 to 2018. He curated a number of exhibitions concerning modern and contemporary art especially in GUTAI group. The representative exhibitions: The Art in Kansai 1950’s-1970’s (1994), Art and Earthquake (2000), GUTAI 1954-1972 (2004), GUTAI: The Spirit of an Era (2012), A Feverish Era: Art Informel and the Expansion of Japanese Artistic Expression (2016-17). His representative publication is What’s Gutai (Bijutsu Shuppan-sha, 2004).