was a Japanese sculptor who resided in both Tokyo, Japan, and Los Angeles, California. A graduate of Tama Art University, he was one of the key members of Mono-ha, a group of artists who became prominent in the late 1960s and early 1970s. The Mono-ha artists explored the encounter between natural and industrial materials, arranging them or interacting with them in mostly unaltered, ephemeral states. Sekine’s signature materials included earth, water, stone, oilclay, sponge, steel plates, among others. His Phase—Mother Earth, consisting of a hole dug into the ground, 2.7 meters deep and 2.2 meters in diameter, with the excavated earth compacted into a cylinder of exactly the same dimensions, is considered to have initiated the Mono-ha movement. Later credited as the "big bang" of the movement, the work not only attracted the attention of fellow Tama students but also Lee Ufan, who was senior to Sekine and in search of a theoretical framework for new art. This work led to an intense intellectual exchange between Sekine and Lee, involving other Tama students, that served as a foundational theory of Mono-ha, that combined Sekine’s principle of “not making” (tsukuranai koto) and Lee’s idea of “the world as-it-is” (arugamama no sekai), setting a stage for themselves and their peers to embark on a full-fledged exploration of mono (things), which became the name for their movement. Sekine’s own work rapidly progressed from Phase—Mother Earth to Phase-Sponge (1968) and Phase of Nothingness - Oil Clay (1969), with all of these works receiving top awards at major competitions. By 1970, Sekine established himself as a young but rising figure of contemporary art, being invited, along with Shusaku Arakawa, to exhibit in the Japanese pavilion at the Venice Biennale in 1970, by the critic Yoshiaki Tōno. While Arakawa filled the pavilion’s interior, Sekine erected a large-scale outdoor sculpture, Phase of Nothingness. Despite these attentions, the artist departed the Mono-ha practice and established Kankyō Bijutsu Kenkyūjo (Environment Art Studio) in 1973 to focus primarily on public sculpture. Early career Nobuo Sekine was born in 1942 in Shiki City, Saitama Prefecture, Japan. From 1962 to 1968, he was a student in the painting department at Tama Art University in Tokyo, where he studied under influential artist-teachers Yoshishige Saitō and Jiro Takamatsu. Takamatsu’s illusionistic paintings and sculpture were central to the development of the Tokyo art scene at that time, as well as his performances and actions that