Aloha Y'All,
According to the Japanese maintenance/erection manual via JACAR (shown below) the "official color" of the Nakajima Type 97 Fighter was:
「機体の外面は灰緑色塗料を塗施す」 or
"Fuselage exterior paint coating is gray-green"
灰緑色 = Hairyokushoku = ash-green color, hence "gray-green."
The second attachment is the Hess-Ives paint mix document found by K. Owaki a few years back showing the Japanese Army aircraft colors. Using the original numbers given these RGB values were posted in 2006 at:
http://japaneseaircraft.multiply.com/photos/album/50/IJA_Colors AFTER posting, we began the comparison to other "knowns". Nick Millman and Ken Glass determined that some of the colors were flawed...due that the Hess-Ives Color System RGB notation used by the Japanese Army/Navy had changed since World War II.
Cheers,
David Aiken, a Director: Pearl Harbor History Associates, Inc.
http://www.pearlharbor-history.org/