This paper explores the flow of funds inside Mitsubishi Bank during the Second World War, focusing on the impacts of acquisition of Daihyaku Bank in 1943 and the Designated Financial Institution System in 1944. Acquisition of Daihyaku Bank substantially expanded the branch network of Mitsubishi Bank, and Mitsubishi Bank utilized those newly acquired branches mainly as a device for deposits collection. A large part of the deposits collected at the branches was sent to the headquarters of Mitsubishi Bank, which, in turn, allocated the funds to loans based on the Designated Financial Institution System, as well to government bonds following the instruction by the National Financial Control Association.