The first official stamps of the Japanese occupation were a set of three issued on April 7, 1943, surcharged and overprinted with Japanese characters and (K.P.). The K.P. stands for Kagamitang Pampamahalaan, Tagalog for Official Business.
Although these were for the use of government offices, the Asociacion Filatelica de Filipinas reportedly acquired "a limited quantity" by special request.
Printing quantity: 2c (200,000), 5c on 6c (one source says 400,000 and another says 500,000 for two overprintings) and 16c on 30c (200,000 for two overprintings).