I am led to believe that the Japanese did not issue coins during the WW2 occupation of the Philippines, only script. Is that true for other nations that the Japanese occupied as well?
Be aware that many of the Indonesian coins issued under Japanese Occupation may very well be fakes. I recall reading that many of the "Shadow Puppet" coins (given that name because of the imprint of the traditional Indonesian theater puppet) were destroyed in transit from Japan or melted down before reaching Batavia (modern day Jakarta). Consequently they are quite expensive if problem free.
Here are some photos. They should be in coin catalogs and Numista under Manchukuo. There were also some issued for other parts of China south of Manchuria later in the war. Bottom photo is "Hua Hsing Bank" 10 Fen, 1940. For the top 2 photos, bottom center is China outside Manchukuo, bottom right is occupied Korea. Rest are various Manchukuo.
You need to get a Krause World Coins 1901-2000 catalog. Also look at this post from in here at CoinTalk: https://www.cointalk.com/threads/a-side-collection-china-under-japanese-occupation.298271/
I actually have a Krause 1901-2000 catalogue which I don't use. If you'd like, I could mail it out to you
Coins were also issued for the "Mengjiang United Autonomous Government" (puppet state in Inner Mongolia):