The war boom stimulated every sort of institution which was in any way involved with money and banking in Japan. Post offices which had operated for a long time, almost since 1868, were by 1900 holding, in the form of small savings, the equivalent of 10 per cent of total banking deposits. These moneys were in effect kept in the trust fund department of the Finance Ministry. They continued to increase in the early 1900s and throughout the war boom. Indeed by 1919, post office savings became the largest resources for direct government needs, amounting to ¥731 million, equivalent to nearly 13 per cent of the total banking deposits.

Another kind of organisation, also important in gathering small savings, was the mujin, or mutual loan associations. Already during the first decade of the twentieth century, mutual loan business was progressing and some organised themselves into company form. In 1914 approximately 830 companies with ¥9.6 million paid-up capital were operating. The Finance Ministry determined to set guidelines for mutual loan business in order to protect subscribers and to ensure that their resources were secure. The result was the Mutual Loan Business Act of 1915 which stipulated that the mutual loan company should have a minimum of ¥30,000 nominal capital of which more than half was to be paid in. Subscribers were required to pay instalment money regularly and the company could lend part of the money by lottery, allowing those subscribers who wished to draw lots.