Courtesy of Jim Lansdale here is an image of an access cover retrieved from the actual Dokuritsu 18 Hiko Chutai Ki-46 in the heading photograph I posted yesterday. It was recovered by a member of the 1st Air Commando who was at the crash site. The exterior paint which is in pristine condition and is an olive or khaki grey colour close to FS 16350 - or exactly similar to the factory paint found on many early Zero fighters. Jim has reported on the paint colours of another Ki-46 artifact in his collection, part of the tailplane and elevator, at j-aircraft.com here and I have rendered the colours described in that report as shown below.
Image Credits: Ki-46 artifact © James L Lansdale; Rendered colour chips © 2012 Straggler