If you are a serious researcher, you need to check eBay and
www.abebooks.com for these 2 books. Do you know the difference between a Sentai and a Kokutai? Rikugun and Kaigun? Ranks: Socho vs Jotoheiso?
Can you understand Japanese dates 20.8.15 (1945 August 15)?
Until I got these handy WWII era reference guides, I had a difficult time understanding Japanese military terminology! These guides not not expensive and well worth it.