Most of these philippine units cannot fight the panese. They wouldn't probably be able to fight them on equal terms. This is a slaughter so this is a plan that was doomed already. And the japanese push inland so fast that you don't realize, unless you look at a time line and match it up to events, how quickly it's happening.
Japan's rising sun goes supernova and engulfs a huge area of Asia and the Pacific. A war without mercy begins to develop infusing the whole conflict with a savage vibe.