IMHO you really need to get the New Vanguard #137 (Osprey) Japanese Tanks 1939-45. You will find several color plates of interest.
I did a spot of research on this a few years back, and was basically instructed not to trust 90% of any color images I might find using Google. The reason? Most are pictures of models or restored tanks that were not painted according to the official scheme.
Here's what I discovered …
There were four official schemes:
#1: 1930s (China) – They used a base color of artillery brown (a medium shade) with patches of light sand, mahogany (dark) brown and dark olive green, often with the yellow disruptive stripes. This was called the four-color camo scheme.
#2: 1940-41 (Pacific) – They used a base color of artillery brown with patches of mahogany brown and dark olive green, often with the yellow disruptive stripes. This was called the three-color camo scheme (they dropped the patches of light sand).
In both of the above cases, sometimes the colors were separated by thin black lines, sometimes not. And the use of the yellow stripes was quite common, but not always present. The colors were most often painted on (by brush) and not sprayed on, so no feathering of colors.
An important note regarding the yellow stripes – and this is the main reason I was told I could spot an improperly painted tank photo. If you viewed the tank from above, you would find two yellow stripes: one going from the front to the back, and another going from side to side. They would most often meet on the turret roof, thus dividing the tank into four sections (again, when viewed from above). These lines would curve quite a bit as they made their way from one side of the tank to the other.
I was told they never used patches of yellow, and they never used more than two lines of yellow (one always front to back, the other always side to side), so any photos you see where there are patches of yellow used, or more than the two bisecting lines of yellow, that tank is improperly painted.
#3a: 1942 onward (Home Islands & China): The IJA decided to standardize their schemes, and opted for a base coat of parched grass (khaki) with patches of mahogany brown and dark olive green. This was referred to as the 1942 three-color scheme (and thus, the earlier three-color scheme became the pre-1942 three-color scheme). The use of black edging, and the use of the disruptive yellow stripes was eliminated.
#4a: 1942 onward (Philippines & Pacific Islands): Identical to the Home Islands scheme except that the dark olive green was replaced with a lighter green called willow green (a bright medium green). This was developed for the Southern Army and can be referred to as the three-color southern scheme.
These two schemes were painted on (by brush) during 1943 so had hard edges to the colors. But starting in 1944 the colors were increasingly applied by spray and the edges of the colors were feathered. For my purposes, I will refer to the feathered edges schemes as #3b and #4b.
It is important to know that once painted, Japanese tanks were often NOT repainted just because the official scheme changed, or their location changed. So you could (and would) find pre-1942 schemes on tanks encountered on the Pacific islands in 1944.
Most of the info above comes from the Osprey Japanese Tank book I mentioned above, plus posts in various forums throughout the net.
You essentially have SIX schemes, since #3 & #4 can be found with hard edges to the colors, or feathered edges. I think the safest scheme to use is either #2 or #4 as they were both designed for Pacific Island campaigns, and between these two, #2 would really work for the entire Pacific war.
One of the color plates in the Osprey shows a Type 97 Chi-Ha on Saipan in July 1944 painted in the pre-1942 scheme with the yellow stripes.
For the Type 95 Ha-Go there are two color plates, one showing the pre-1942 scheme (with yellow stripes) on a tank in the Philippines in 1941, and another which is a cut-away diagram showing the 1942 southern scheme on a type 95 on Iwo Jima in February 1945.
Sorry to blather on so long, but having spent a great bit of time trying to track down this info, I am more than happy to spare others that research! Hope this helped.
Steve