Japan's megabanks are turning their attention to a long-neglected cornerstone of the national economy: the small and medium-sized businesses that make up 99 percent of Japanese firms and account for 70 percent of all bank lending. As the Bank of Japan raises interest rates to levels unseen since 2007, SMBC, Mizuho, and MUFG are each launching digital platforms designed to embed themselves in the daily financial lives of these enterprises. The urgency is as much strategic as it is economic — in a tightening margin environment, the bank that becomes essential infrastructure for small business ma