WEBSumitomo Mitsui Financial Group. Website. www .smbc .co .jp. Sumitomo Mitsui Banking Corporation (株式会社三井住友銀行, Kabushiki-gaisha Mitsui Sumitomo Ginkō, SMBC) is a Japanese multinational banking financial services institution owned by Sumitomo Mitsui Financial Group, Inc (株式会社三井住友フィナンシャル ...