After arranging an affiliation between Ube Industries and Nippon Rayon in 1954, Sanwa began promoting industrial transactions between its major customers, formalizing the process in the early 1960s through the establishment of special promotion units.
The three largest members of the group (Hitachi Shipbuilding, Ube Industries and Teijin) had relatively independent positions with no cross-shareholdings.
[1] The Sanwa Group held a collective exhibition at Expo '70 in Osaka called Midori-kan (みどり館).
Later that year, 31 Sanwa Group members formed Midori-kai as a joint venture company.
It eventually grew to 157 members, serving as a common HR, insurance and business support platform.