You have one example of "Occupation Currency" or "Invasion Currency" printed by the Japanese - they also made Shillings, Rupees, Pesos, and even US dollars. You can see examples of some of them at my museum:
The Centavo notes were made for use in the Phillipines and are usually found in 1, 10, and 50 Centavo denominations. Like other types of collectible currency, the letter codes help determine the value, although these notes, especially the Centavo type, are very common. The most difficult one for me to find was one in Dollars.