John B. what you will find using the FS color chips (I have them is that there is a "near" match for the Japaneese colors but not an exact match. The FTE book contains Japaneese colors and that's what I would recommend getting.

An understanding of the FS color chip system. These colors are used but the USA and are standard colors bought for and used by the US Govt. They are NOT reference colorchips intended for the rest of the world colors. As it turns out there ARE many colors that are the same or near the same those used by other countries.
So an attempt was made by the Plastic Model society to standardize the world colors using the FS color chips and then descirbing the subtle and important differences where applicable. More often than not an exact match to a foreign color of WWI through WWII is not available as a chip and a mix needs to be made to get the correct color.

Testors Model Masters, Humbrol, and some others do offer their brand of Traditional WWII colors. These don't always agree with one another in color.. so the bottom line is.. if you are competing.. A. Get a source of color that is recognized by the various competition organizations such as FTE's color guide OR at Recognized Color sourse such as contained in a recognized publication (book). and then B. Match your colors to your recognized source.
Of course photographs of your subject are acceptable as a color reference and you can match your colors to them... if the lighting is right.