Collective improvisation group begun in 1958 by Takehisa Kosugi and Shukou Mizuno; two students at Tokyo National University of Fine Arts and Music. They were soon joined by other music students Chieko (Mieko) Shiomi, Mikio Tojima, Genichi Tsuge, and Yumiko Tanno, as well as Yasunao Tone from the Department of Literature at Chiba University. The group wasn't named until 1960 on the occasion of their participation in "Dance and Music: Their Improvisational Conjunction" performance at Chiya Kuni Dance Institute, Tokyo. By 1961, Yumiko Tanno had left the group. After their concert at Shogetsu Kaikan Hall in September 1961, the focus of the group changed from improvisation to being a flexible ensemble for members of the group. After that, the group was reduced to Kosugi, Shiomi, Tone and Mizuno, and during 1962 most of the performances were by just Tone and Kosugi. They were rejoined by Mizuno for their performances in 1963 and their reunion concert at the Cross-talk/Intermedia festival in 1969.
Many of the group's few performances were at dance concerts, symposiums and festivals, but they also performed at recitals of music by Toshi Ichiyanagi and Yoko Ono, as well as member Yasanao Tone's one man exhibition at Minami Gallery.