The Philippine Veterans Affairs Office has digitized the NARA records pertaining to the Philippines in World War II. They can be viewed at Welcome - Philippine Archives Collection. The records include the files on Philippine guerrillas, USAFFE and Philippine Army records from 1941-42, and US Army records from 1944-45 pertaining to the liberation of the Philippines.
I think this link has been posted elsewhere, but it's good to have it in its own topic for easier access. There are a lot of great documents to access.