Key Hiraga (1936–2000) has been the subject of retrospective exhibitions at Studio Gariboldi, Milan (2015), The Mayor Gallery, London (2008), Hiratsuka Museum of Art, Hiratsuka (2000) and Bokushin Gallery, Tokyo (2000) and has featured in multiple survey exhibitions including Japanese Anti-Art: Now and Then, The National Museum of Art, Osaka (1991), Japanese Ways Western Means: Art of the 1980s in Japan, Queensland Art Gallery, Brisbane, Australia (1989), The 1960s: A Decade of Change in Contemporary Japanese Art, Tokyo National Museum of Modern Art (1981), Japanese Artists from Europe, National Museum of Modern Art, Kyoto (1972), 10th São Paulo Biennial, São Paulo (1969), The New Japanese Painting and Sculpture, Museum of Modern Art, New York (1966), La Figuration Narrative dans l’Art Contemporain, Galerie Creuze, Paris (1965). He died in Hakone in 2000.