Sumitomo’s history goes back to the Kan-ei era in 17th century Japan when Masatomo Sumitomo opened a shop selling books and medicines in Kyoto.
Masatomo wrote the Monjuin Shiigaki or Founder’s Precepts to offer guidance on how a merchant should conduct business. This document summarizing his teachings is the foundation of Sumitomo’s business philosophy.
At around the same time, Riemon Soga, the husband of Masatomo’s elder sister, was engaged in copper refining and coppersmithing under the name “Izumiya” in Kyoto. Acting on hints gained from the Portuguese and as a result of his great efforts, he developed the nanban-buki technique for separating silver from unrefined copper.
Tomomochi Sumitomo, the eldest son of Riemon Soga, married a daughter of Masatomo and joined the Sumitomo family. He moved the business to Osaka and, in partnership with his father Riemon, made the nanban-buki technique available to other members of the copper-casting guild in the city. Sumitomo/Izumiya earned their respect as the originator of the nanban-buki technique. At the same time, Osaka became Japan’s center for copper refining.
In the Edo period (1603-1868), Japan was one of the world’s leading copper producers. Building on Sumitomo’s strength in copper trading, Tomomochi expanded the business to include thread, textiles, sugar, medicinal herbs, and a host of other items. Furthermore, a branch of the family started a money-changing business. Operations flourished to such an extent that people said, “Izumiya is unrivaled in Osaka.”