As you have undoubtedly learned in your historical studies so far, any research paper on a military campaign should draw when possible from primary sources on both sides. Fortunately for those studying the campaign in Luzon (or any other campaign in the Asia-Pacific theater of World War II), a great deal of original Imperial Japanese Army and Imperial Japanese Navy records from World War II are available in translation.
One critically important body of translated Japanese primary sources relevant to the Luzon campaign are a collection of statements made by former officers of the Imperial Japanese Army and Imperial Japanese Navy in the years immediately following the end of the war. They were collected by U.S. Armed Forces authorities who then had them translated. This collection of Japanese officers' statements are known to historians and archivists as simply the Japanese Monographs series. The series overall is sometimes known also by the title Japanese Studies in World War II. You will see it cited this way in Robert Ross Smith's Triumph in the Philippines, for example.
As you realize, of course, historians must use all primary sources with care, constantly scrutinize them and use subjective judgment to make decisions about whether and to what extent their testimony is useful. This is especially the case with the surviving records of the Japanese Monographs collection. These sources can be quite important in your work, but it is essential that you become familiar with their background and the history of how they arrived before us to use today. The process began in October 1945 when HQ, Far East Command started collecting former Japanese officers' statements. A few years later they were transferred to the U.S. Army Office of the Chief of Military History where scholars discovered significant errors and gaps in many of them. Accordingly, Far East Command gathered teams of U.S. Army historians and former Japanese officers to edit the original statements and improve the translations. This work continued throughout the early 1950s, and many of the resulting statements were used by authors of the U.S. Army official histories volumes, such as Robert Ross Smith's Triumph in the Philippines with which you should definitely be familiar. To learn more about the origins of these important primary sources and their usefulness to historians studying the Luzon campaign, refer to Smith's bibliographic essay "The Sources: A Critical Note", especially his section "Sources of Japanese Information" on pp. 700-704. Reviewing that section may direct you to other useful translated Japanese sources as well.
In the decades the editing work the paper typescripts of the statements were microfilmed. In 2020, a library consortium to which USMA belongs, called Center for Research Libraries (known by its acronym CRL) digitized that microfilm and now it is available to you online. You can find a description in the CRL catalog here which provides links to digital files of each individual monograph. In some cases, the lack of clarity of the scans may surprise you but you are seeing scans of microfilm made decades ago. That microfilm itself consisted of imperfect photographs of typescripts made even earlier that were never easy to image themselves in the first place. So you will be looking at modern copies of older imperfect copies that were themselves made of imperfect originals. Yet the ARE useable. Do not be deterred; almost all are legible enough to use if one makes adjustments using the standard features of .pdf reader applications. Learning to accommodate the imperfections of copies is part of the historical process but it is definitely worth the effort.
Using the Japanese Monographs series digitally
The Army offices that first collected the monographs first organized them sequential numbering but as a result of the complex editing process described above were renumbered by another numbering scheme over the years. On the one hand, you may find this at first confusing and cumbersome. On the other hand, part of learning the historians' craft is to learn that the preservation of the historical record often results in these kinds of circumstances. Part of the historian's task is to navigate circumstances like these. Yet it is always worthwhile. With just a little effort you will have before you an invaluable primary source insight into what decision-makers on the other side were thinking. This can only enrich your paper. If you are using Robert Ross Smith's Triumph in the Philippines, you will have noticed that Smith often cites various particular volumes in this series. One that you may find useful is 14th Area Army Operations on Luzon. Note that Smith refers to it as No. 125 of the series; owing to the renumbering mentioned above it is now no. 7. In the Center for Research Libraries catalog record, click on "available online" and then using the panel at the left navigate to other images for No. 7.
If you discover other volumes in the series, whether from Smith's citations or from citations in other works, a guide to the whole series, showing the current numbering scheme that you need to navigate to the right file in the CRL record is available on a guide from the collections of Ibiblio (another consortium important for military history digital materials).
To use it, search for the title of the particular volume in the series that you want, note the number, and navigate within the CRL record the right number.
Remember also that Smith calls the overall series by its alternate title, Japanese Studies in World War II. Therefore when you see a particular title of that series mentioned in his footnotes, you can still use the instructions in this section to find it.
For additional help using the Japanese Monographs series, set up an appointment with the Military History liaison librarian, Dr. Mark Danley at firstname.lastname@example.org (available by remote reference service during the Spring 2020 semester).
Although the volumes of the Japanese Monographs series are important primary sources for the IJA and IJN perspective, many others are available. Examine the items below for more ideas of using other bodies of translated Japanese primary sources.