Through his collaborations, writings, and teaching, he promoted an interdisciplinary avant-garde in postwar Japan that served as the foundation for the emergence of Japanese media art in the early 1980s, a field in which he remained active until his death.
His family home in the Ōimachi district also featured an annex designed by and decorated with paintings by the modernist Japanese painter Seiji Tōgō, although it was severely damaged by bombing during the war.
Omuka thus posits this annex as a possible source of Yamaguchi's interest in industrial materials, urban space, and modernist forms reminiscent of Bauhaus design.
He participated in the Avant-Garde Artists' Club's Summer Modern Art Seminar in July 1948 and formed the Shichiyōkai group with Shōzō Kitadai and Hideko Fukushima, among others, in August 1948.
[6] Yamaguchi's perspective on art was further tempered by exposure to materials on László Moholy-Nagy, György Kepes, and other modernists through the American-run CIE Library at GHQ during the American occupation.
[6] The combination of these distinct but inter-related experiences helped Yamaguchi solidify a commitment to the potentials of a cross-disciplinary collaborative approach to artmaking that he then put into practice as a member of the seminal group Jikken Kōbō.
[6] Yamaguchi co-founded Jikken Kōbō in 1951 alongside artists Shōzō Kitadai, and Hideko Fukushima; composers Tōru Takemitsu, Jōji Yūasa, Kazuo Fukushima, Keijirō Satō, Suzuki Hiroyoshi, and Tetsurō Komai; poet Kuniharu Akiyama; photographer Kiyoji Ōtsuji; lighting designer Naoji Imai; pianist Takahiro Sonoda; and engineer Hideo Yamazaki.
These more architectural painterly objects provided Yamagichi the chance to collaborate with architects including Kiyoshi Seike and Kenzō Tange as he embedded the vitrines into concrete wall structures or expanded them into wall-sized light-box partitions.
[12] During the latter half of the decade, Yamaguchi began to articulate an idea of expanded sculpture in his 1967 book Futeikei Bijutsu-ron (Theory of Indeterminate Art), exhibited in the Venice Biennale (1968), and became commissioner for the Mitsui Pavilion at Expo ’70.