Here's something which is more related to experimental or contemporary classics than to Free Jazz/Improvisation. But it is improvised as well...
Takehisa Kosugi was later co-founding the "Taj Mahal Travellers" and since 1978 he served as the musical director of the Merce Cunningham Dance Company..
He, Yasunao Tone and Chieko Shiomi were also associated with the Fluxus movement.
More information on Takehisa Kosugi > http://en.wikipedia.org/wiki/Takehisa_Kosugi &
http://www.lovely.com/bios/kosugi.html & http://www.artpool.hu/Fluxus/Kosugi.html
Yasunao Tone > http://en.wikipedia.org/wiki/Yasunao_Tone
http://www.lovely.com/bios/tone.html & http://www.thewire.co.uk/articles/208/
also > http://www.shukomizuno.net/
Track 1 & 2:
Takehisa Kosugi, Chieko Shiomi,Yumiko Tanno, Yasunao Tone, Shukou Mizuno
3. Metaplasm 9 - 15
Track 1 & 2 on May 8, 1960 at Mituno's House.
Track 3 on September 15, 1961 at Sogetsu Kaikan Hall, Tokyo