Gutai group

The Gutai group (具体； means "tangible; material; concrete") was an artistic movement and association of artists founded (according to most sources) by Jiro Yoshihara in Japan in 1954. According to the official website of Shozo Shimamoto, Shimamoto and Yoshihara founded Gutai together in 1954, and it was Shimamoto who suggested the name Gutai, which means (again, according to this source) “concrete” (as opposed to abstract/theoretical).

The Gutai Manifesto
Yoshihara wrote the manifesto for the Gutai group in 1956. The full text of the "Gutai Manifesto" is available in English at the website of Japan's Ashiya City Museum of Art & History. Among its preoccupations, the manifesto expresses a fascination with the beauty that arises when things become damaged or decayed. The process of damage or destruction is celebrated as a way of revealing the inner "life" of a given material or object:

"Yet what is interesting in this respect is the novel beauty to be found in works of art and architecture of the past which have changed their appearance due to the damage of time or destruction by disasters in the course of the centuries. This is described as the beauty of decay, but is it not perhaps that beauty which material assumes when it is freed from artificial make-up and reveals its original characteristics? The fact that the ruins receive us warmly and kindly after all, and that they attract us with their cracks and flaking surfaces, could this not really be a sign of the material taking revenge, having recaptured its original life?...." 

Influence
In addition to Yoshihara and Shimamoto, members of the Gutai group included Sadamasa Motonaga fr:Sadamasa Motonaga, Atsuko Tanaka, Akira Kanayama, and others. A formative influence on the later Fluxus movement, the group was also associated with certain European (particularly French) art world figures such as Georges Mathieu and Michel Tapié, and with tachisme ("art informel"). According to the Tate Gallery's online art glossary, Gutai artists also "created a series of striking works anticipating later Happenings and Performance and Conceptual art." Gutai artists also created works that would now be called installations, inspiring the work of non-Japanese artists such as Allan Kaprow and Conrad Bo, and leading to the later Fluxus network.

The Tate article records that "the group dissolved in 1972 following the death of Yoshihara."