Tom, @tom-bebout
Tom Cleaver's @tcinla
comments about how this kit build up are spot on. I'm sure you have found this out by now.
However, as far as the colors he mentioned on the fabric covered controls, he is off. We all know the Ki-100 was a direct descendant of the Ki-61 Hien, (Allied code name Tony). These aircraft had all of their control surfaces painted using aluminum colored dope. Some of the Ki-61's were actually completed as Ki-100's with the radial engine being installed, and the forward fuselage modified to accept the new engine. This was done when the license built DB engine was in short supply because of the efforts of the B-29 crews. Then these Ki-61 airframes with the radial engines were also called Ki-100's. Here's a cool picture I found online showing a Ki-61 assembly line.
Up until just recently I too thought these planes had used the IJA Light Gray, but then I discovered a document that was written by an expert on the subject who lives in Japan. I have a copy of this paper stashed in my hobby library, but I'll now go digging for it so I can post it here should you be interested.
Meanwhile, here are a few pictures of an Akeno Flying School Ki-61 for you to use in case this matters to you. This plane was operated (at least for a while) in a bare metal finish. You can see how the controls have the same appearance as the surrounding bare metal.
Look very close at this next picture. It has a lot of hidden information in it. This photo shows another Ki-61 assigned to the Akeno Flying school. Notice how the controls have a slightly different look to this. I firmly believe this is caused by sunlight, and not having the flying controls centered. This is an illusion that is cast by having light reflect off the surface at a different angle, creating a slightly different looking color. Now look at the rudder, and how it matches the fin. This is because the rudder is centered or "neutral".
But since this is a Black and White picture to begin with, it's very hard to know for sure. This is why I'm going to dig out the article that was written on a Japanese aircraft, by a Japanese expert, who also happens to live in Japan and speaks Japanese. This last part of the sentence is very important, as some meaning can be lost during translations from Japanese language to English. Once I find it I'll post it for you.
Here's a photo showing another "Hien" that has flipped on it's back after a hard landing. The underside is now visible in this picture. So is the "Port" side aileron. It too matches the surrounding bare aluminum color.
The Japanese started switching over to the "Aluminum" colored dope for use on the control surfaces sometime during the production run of the Ki-44. Part of the Ki-44's had the IJA Light Gray color on the fabric controls, while the rest used Aluminum colored dope to tighten and seal the fabric.
Here you can see the rudder is a "darker" shade that the rest of the airframe on this next picture of a Ki-44. This effect "could" be caused by having the rudder slightly offset from neutral, and it simply could be the effects of sunlight casting a shadow. It could also be an example of the IJA using Light Gray on the part, since it was fabric covered.
Now take a good look at this next picture, also showing another Ki-44. This aircraft seems to have it's rudder and ailerons painted using Aluminum dope. You can't really get a good look at the elevators, because the control stick is pulled back and these parts are no longer centered. If I was a betting man, I would "think" these elevators were also painted using Aluminum colored dope.
I discovered this information several years ago when I was doing my research for all of the article I had planned on writing about the various different colors that were used on the Japanese aircraft. Now I have decided that I might simply write a book on the subject instead... If this indeed happens, I'll let everyone here know.
Bottom line however is this is a hobby. It's your plane, so you should build it and paint it in the colors you want to... Have fun with it.
I simply wanted to let you know that the Imperial Japanese Army didn't use the color "Light Gray Green" on everything as we once thought.
Hope this helps. Stay safe my friend.