By the early 20th century, saving deposit investment funds managed by the Ministry of Finance (MoF-SDIF), which were mainly derived from postal savings deposits, had developed into a relatively large financial aggregate, as large-scale capital accumulation was now occurring outside of the "multi-layered financial structure" formed by the Bank of Japan and commercial banking system. However, the research to date on the subject seldom delves into the actual management style and specific influence of such MoF investment funds, merely assuming that during the World War interim period, there was some financial route in place for plowing MoF-SDIF (according to guidelines set in 1909) back into local economies through special financial institutions, such as the Nihon Industrial Development (Kangyo) Bank, agri-industrial banks and the central financial depositories of industrial cooperatives. This article attempts to clarify the characteristic structural features of that investment route and the process by which it was firmly put in place. To begin with, in the absence of legal provisions governing the management and use of SDIF, investment routes and practices were established by custom within the actual process of distributing the funds. As to how the system of plowing SDIF back into local economies was providing capital through the above-mentioned special financial institutions in response to the capital demands of society as a whole and regarding the influence of the system on local society and its financial structure, it functioned to reorganize existing financial institutions and their structure of transactions by providing a modernized financial assistance bridge to individual industrial cooperatives, small and medium scale businesses and existing locally based organizations. The author then turns to the institutional and regional issues involved, by citing specific cases of how the system's role in providing economic relief funds on an individual basis was perceived in determining the character of the financial system as a whole. In more concrete terms, the author focuses mainly on the case of Nagano Prefecture, describing the influence of the system after the firm institutional establishment of the MoF savings deposit department during the Meiji era in organizing the first nationwide relief funding effort following the outbreak of Word War I and providing relief finance during economic downturn which marked the war interim period.