Three brothers Sumitomo Masatomo, Tomomochi, and Soga Riemon started the Zaibatsu by combining their factories.

The House of Sumitomo established a close relationship with the Tokugawa shogunate so they could export large quantities of copper despite the general ban on overseas trade.





In the 1930s Sumitomo became one of the largest zaibatsu in Japan, and during World War II it controlled at least 135 companies.

A little while after World War 2 the Sumitomo zaibatsu was disbanded.

Sumitomo Zaibatsu

Sumitomo Masatomo

Sumitomo began to diversify into such interests as copper products and steelmaking and later into chemicals and machinery.