Not to be confused with Sumitomo Life Insurance Company, a mutual insurance organization.Mitsui Sumitomo Insurance Group Holdings, Inc. (三井住友海上グループホールディングス株式会社, Mitsui Sumitomo Kaijō Gurūpu Hōrudingusu Kabushiki-Kaisha) is a Japanese insurance holding company headquartered in Tokyo, Japan.MSIG was formed in 2001 from the merger of Mitsui Marine & Fire Insurance Co. and The Sumitomo Marine & Fire Insurance.