On May 4, 1895, Iba convened the first jyuyakukai (executive board) meeting of the House of Sumitomo at the Onomichi Branch. The members included Teikichi Tanabe, who was general manager of the Osaka Head Office, and Jyusaku Teshima, Teikichi Den, and Kanji Tani, all three of whom were riji (directors). The agenda addressed such issues as establishment of the Sumitomo Bank and expansion of foreign trade. Based on resolutions passed at that momentous meeting, The Sumitomo Bank was established on November 1, 1895, and the Wakamatsu Branch (predecessor of Sumitomo Coal Mining) to supervise the coal mines in the Chikuho area of Fukuoka Prefecture was established on February 12, 1896. On April 1, 1897, Sumitomo Copper Works (predecessor of Sumitomo Metal Mining, Sumitomo Electric Industries, and Sumitomo Light Metal Industries) was established. On May 9, 1898, the Forestry Department and the Civil Engineering Department of the Besshi Copper Mines (predecessors of Sumitomo Forestry and Sumitomo Construction, respectively) were established. On July 1, 1899, Sumitomo Warehouse was established, separate from the bank. Thus, today’s major Sumitomo Group companies trace their histories back to this period when Iba served as the director-general of the House of Sumitomo.
On October 1, 1896, Iba made extensive revisions to the Rules Governing the House of Sumitomo as they were increasingly out of step with the actual circumstances of business in the late 19th century. The main revisions were 1) abolition of jyuninkyoku (the senior management department) and instead deliberation of important matters by jyuyakukai (the executive board), 2) renaming of sorinin as soriji, and 3) making riji (directors), who were previously below the general manager in the hierarchy, members of jyuyakukai (the executive board). These moves signaled the launch of Sumitomo’s soriji (director-general) system and jyuyakukai.