In the late and much lamented Asahi Journal, Vol.3 No.4, Tom Hall cites a relic from a 1 Shiki Rikko (Ichi Shiki Rikujoh Kohgeki-ki - Type 1 Land-based Attack Aircraft - 'Betty'), belonging to noted colour researcher and collector James F Lansdale, as revealing "a dark chocolate colour around FS 20059". In the article it is mentioned that Jim Lansdale felt that at least one other brown was used.
At first glance this colour seems to bear little relevance to any of the Kariki 117 chips but when one considers the FS 20045 match for N0 provided by Ryôichi Watanabe a slightly different picture emerges. The difference between 20059 and 20045 is 4.02. There is no equivalent Navy colour identified by Don Thorpe but curiously the closest FS match for his Army colour A11 Dark Brown(Munsell 10R 2/2) is also 20059 @ 5.35.
This dark chocolate colour appears frequently in artistic representations of Navy aircraft, but is again quite distinct from the yellowish and medium reddish browns discussed earlier.
In Model Art 510 H2 (see previous posts) is matched to FS 30099 and this colour was also cited in a post about 1 Shiki Rikko colours at j-aircraft.com by François P Weill. The basis for this match is unknown. However, it is difficult to discern a close similarity when comparing the H2 facsimile chip to FS 30099.