These are an interesting collecting area, and most notes are relatively inexpensive. The Japanese issued 35 different occupation notes for China and Indochina, 14 notes for the Dutch East Indies, 10 for Malaya, 13 for Philippines, 9 for Burma and 4 for Australia. Obviously the Australian notes were never used !
Prior to this they issued military notes for the Sino-Japanese War, Russo-Japanese War, Tsingtau Expedition in 1914-15 and the Siberian Expedition in 1919-20. Most of these earlier notes are scarce and expensive with almost no examples of Sino Japanese War notes surviving.