by Yoshihito Kurosu

translation by Ryutaro Nambu


1.1. Birth of Reisen and its Background

In 1937, Mitsubishi started the development of A6M1 12-shi Kanjo Sentoki (Type 12 Experimental Carrier Fighter). The 12 corresponds to 1937, the twelfth of Showa era under Emperor Hirohito's rein.

In that same year, 1937, IJN imported thirty (or twelve) He-112 fighters from Germany, and gave them a fighter designation "A7He1". Those He-112s were painted in RLM63 Grungrau.

The first prototype of 12-shi (pronounced "ju-ni-shi") flew in April 1939, followed by the second machine in October 1939. The third machine, with a new Sakae engine, was completed around December 1939 or January 1940. Deviating from IJN's standard orange color for experimental and prototype aircraft, Mitsubishi painted those prototype machines in "hai-ryokushoku" (literally ash green, meaning greenish ash). [see Appendix B: Color Names in Japanese]

In July 1940, IJN adopted A6M2 officially as Rei-shiki Kanjo Sentoki (Type 0 Carrier Fighter). The "0" (pronounced "rei") in the designation means 2600 in the Japanese Imperial era, which translates into 1940AD. (Similarly, 99 of D3A means 2599 or 1939AD.) Exact translation of "kanjo" is on-shipboard or embarked.

Before IJN introduced Rei-shiki Kanjo Sentoki (often dubbed Reisen or rather colloquially Zero-sen), it used to paint its carrier fighters in silver overall. No gray examples were known. Apart from carrier fighters, Aichi D3A Type 99 Carrier Dive Bomber (99-kanbaku), Mitsubishi F1M Type 0 Observation Seaplane (Reikan), and Aichi E13A Type 0 Reconnaissance Seaplane (Reisuitei) were possibly painted in "mei-kaishoku" (light ash, IJA notation "J1". Some people call that color "mei-kai-hakushoku" or "mei-hai-hakushoku" (literally light ash white, meaning light whitish ash).

No IJN documents known today state that protective clear topcoat was applied to Zeros or to any other navy fighters. Among the existing photos of Mitsubishi A5M Type 96 Carrier Fighter (96-kansen), a few machines seem to have somewhat darker shade than the ordinary silver finish. Some researchers speculate that the darker look was from a possible application of tinted topcoat. It may as well be attributed, however, to photographic conditions such as light, exposure, film characteristics, use of filter, and development process. IJN veterans remarked, as I overheard from a reliable researcher, that they had seen Type 96s with a field-applied protective topcoat of slightly tinted varnish (or dope?). But there is no evidence whatsoever that Zero received a similar topcoat.

1.2. Kugiho No. 0266 report

IJN's Kugisho (short for Koku Gijutsu Sho or Air Engineering Arsenal) carried out a series of camouflage test at Yoko-ku (short for Yokosuka Kaigun Kokutai or Yokosuka Navy Air Group) between November 1941 and February 1942. Kugisho summarized the test results in "Kugiho"[Air Engineering Report] No. 0266: Research on Camouflage for Type 0 Carrier Fighter (Research on Aircraft Color Schemes)". The 0266 was navy's classified document, of which perhaps less than a hundred copies should have existed. A copy, known to be the only one existing today, is in a private collection and not disclosed.

In the 0266, two grays, J2 ("sei-kaishoku" or bluish ash) and J3 ("haiiro" or ash), were reported, together with greens. Sample color chips were attached to the 0266 copy, but their tones have not been confirmed by matching to FS, Munsell, or Methuen chips, as the current owner does not disclose them. J1 was not tested in the 0266, and no color chip was attached. IJN's standard colors, including J1, J2, and J3, were originally glossy. Additives were used to give the colors matte finish in the tests.

In search of an effective camouflage scheme, the Kugisho team compared the experimental colors against the standard Zero scheme. The reporter of the 0266 wrote about the standard Zero color as follows:

"The color of gen-yo Type 0 Carrier Fighters is similar to a J3 (haiiro) slightly tinted with ameiro, but differs from the experimental colors as it has luster."

"Ameiro" in Japanese literally means candy-color or caramel-color, but is commonly used to mean transparent yellowish brown, brown, or light brown, such as honey, maple syrup, and amber. "Gen-yo" translates to "currently in service" or "now in use".

In other parts of the report, the 0266 reporter temporarily called that gen-yo color as "ameiro" or "gen-yo ameiro" for brevity. The report consists of lists and short comments, where nonce words like them may have served well for conciseness. Such use of the word "ameiro" was only temporary and exceptional by the 0266 reporter alone, and no other official IJN documents known today use such expressions, not even a single mention.

1.3. J3 and two-color camouflage

J3 was called "haiiro" (ash) in the 0266. But As I heard directly from two reliable researchers who had seen the existing 0266 color chips, J3 was like RLM63. One of them remarked: "J3 was close to RLM63 in hue, but much lighter than RLM63."

The 0266 concluded from test results that "no-ryoku-kokushoku" (deep greenish black) as an upper surface color had a good camouflage effect from its low visibility.

In July 1943, IJN HQ issued a directive specifying a two-color camouflage scheme. Field application preceded the directive; units on the tropical fronts began practicing a top-side green camouflage since around the summer of 1942.

The colors of the two-color scheme were not strictly kept to the norm. Nakajima's colors were different from Mitsubishi's colors. And the colors may also have varied over time. For instance, Mitsubishi's later color for top-side was a very deep shade of dark green, much darker than its earlier color. Similarly, the lower surface color ranged from haiiro to hai-ryokushoku.

The "Hiko-ki Keikaku You-ryou-sho Kaitei-an" (Proposal for the revisions of aircraft planning procedures) issued by Navy Air Command HQ in March 1944 has a table of standard colors and codes under "Kari-kikaku 117 Shiki-betsu Hyojun" (Provisional Standard 117 Color Norms). The table specified the upper-surface color as D1 "an-ryokushoku" (dark green) and the lower-surface color as J3 "hai-ryokushoku" (greenish ash). Notice that J3's notation was different from the 0266, in which it had been called "haiiro". (I will touch on this difference in Section 3.1.)

The A6M5 Zero Model 52 on display in the Smithsonian National Air and Space Museum, famous for its strict and precise researches and restoration, is painted in dark green similar to Munsell 10G3/2 on upper surfaces and in light gray similar to Munsell N7.5 on lower surfaces. That particular machine was captured on Saipan Island in April 1944, was sent to the U.S., and underwent an evaluation program with all of its markings and colors stripped for complete inspection. The Museum restored the machine to what a Zero at Saipan should have looked like in early 1944. Although the machine was actually made by Mitsubishi, the Museum painted it in Nakajima color version. The tailcode too was of one of Nakajima-made machines. More information on this machine is available at the Institute's WebPages at: http://www.nasm.edu/nasm/AERO/AIRCRAFT/a6m5zero.htm

1.4. Examinations of relics

Mr. James F. Lansdale made an extensive study of existing Zero relics that he and other researchers matched against FS595b color chips. Mr. Lansdale reports that some samples with weathered or faded surface showed chalky pale gray close to FS36357, FS36492, or FS36495. When the samples were "lightly buffed", as he explains, many of them revealed olive-gray colors (beneath the weathered surfaces) close to FS16350, FS24201, or Munsell 7.8Y5.5/2.5.


In his book "Reisen", Jiro Horikoshi, Mitsubishi's chief designer of Zero, recalled: "12-shi was painted in dimly-shining hai-ryokushoku except black engine cowling."

The famous ace pilot Saburo Sakai, who flew Zeros since his early days at 12-ku (short for "Dai 12 Kaigun Kokutai" or 12th Navy Air Group), writes in some of his books that Zero's color was "mei-kaishoku" or light ash. He also writes about his first impression of Zero in his 1992 book "Zerosen no Shinjitsu [The Truth of Zero]" as follows:

"Till then, IJN warplanes always sported brilliant silver overall with bright-red hinomaru. As Zero was introduced, the color scheme changed to haiiro. Zero looked something like aircraft borrowed from some foreign country. In contrast to 96-kansen's sharp and sturdy appearance like a keen-edged sword, Zero looked sleek, smooth, and somewhat feminine."

Mr. Sakai has a light bluish ash sample that corroborates his memories. His sample was taken from the relics of his plane recovered in 1994 from the clear-water swamp near Henderson airfield in Guadalcanal.

In his book "Koga's Zero", Jim Rearden quoted Lieut. Comdr. Eddie R. Sanders, a U.S. Navy pilot who tested the Zero captured at Akutan Island of Aleutian Islands, as reporting: "The original finish was a very smooth light gray, tinted with blue light green." (I think this report quite credible, for it covers technical details of a relatively new machine in its condition soon after the capture.)

I had a chance to talk with a senior modeler, who used to work for Kugisho when he was young. His model of Zero was painted in light greenish ash. He asserted: "As far as I have seen, the early standard color of Reisen is nothing but THIS color. I have never seen a brownish or mei-kaishoku variant. This color was unique to Reisen, and not used for 97-kanko [B5N] or 99-kanbaku [D3A]."


3.1. J3 versus the "gen-yo" color

To describe J3, Provisional Standard 117 used the notation "hai-ryokushoku" rather than "haiiro". I think 117's notation is more precise and indicative than 0266's notation about the actual tone of J3. It is not inconsistent that J3 actually had a greenish tint and that the 0266 reporter described such color as haiiro; hai-ryokushoku is part of colors broadly categorized as haiiro. Conversely, if J3 had had no green content, then the 117 should have not called it hai-ryokushoku. As the two researchers confirmed, J3 was not a plane gray but a gray with a greenish tint.

Then what about the color of gen-yo Zeros? As I judge from the known facts, it was not a paint batch variation within the J3 specs, but what you may call it "Zero special", a separate color expressly prescribed by Mitsubishi for Zero. (I coined the name "Zero special", which I think is better than the misleading "ameiro". I will explain more on this issue later in Section 3.5.) No matter what you name it, the gen-yo color was a glossy light greenish ash (hai-ryokushoku) slightly brownish or yellow-brownish than the J3 of 0266 sample chip.

It is incorrect to reason that gen-yo Zeros were painted in J1, or that J1 was "ameiro". If J1 had been the standard Zero color, the 0266 reporter should have remarked as such. He should have simply written "The color of gen-yo Type 0 Carrier Fighters is J1, similar to J3 but slightly tinted with ameiro...". Likewise, if J1 had been commonly called "ameiro" then he should have written "The color of gen-yo Type 0 Carrier Fighters is similar to a J3 (haiiro) slightly tinted with J1 (ameiro)...". He did neither. That suggests the gen-yo color was not J1; J1 was not ameiro; and of course, gen-yo color was not ameiro either. Then what could J1 have looked like? I am almost sure that J1 was a plain light gray (mei-kaishoku). A researcher whom I trust said so, and I accept his remark as reasonable.

3.2. Paint aging

Both vehicle and pigments of paint age over years. The vehicle, clear and uncolored when fresh, becomes dull, darkish, brownish, or yellowish. Pigments of some colors are stable, some are fragile, and the speed and the extent of aging vary with colors. Weathered and exposed to sunlight, paint loses its luster in short time, and its surface often becomes chalky. Acid and other chemical substances contained in air, rain, and soil also affect painted surfaces.

I sincerely respect Mr. Lansdale's systematic approach and the hard facts he confirmed. His study gave me a solid ground to build my interpretation on. The relics suggest what the original colors might have looked like.

The relics presumably had been exposed to sunlight and rain or in contact with soil over many years before their recovery. If we "sand" or scrape the weathered surface, instead of just lightly buffing it, the inner layer may reveal a color closer to the original condition. Besides, the inner layer may as well have gone through aging. When assessing original colors from the existing relics, it is always essential to compensate for the aging effect of paint, vehicle in particular. I suppose that the color of the relics looked different from FS16350 or FS24201 in their original, factory-fresh conditions some fifty years back.

3.3. Influence of imported He-112

What made Mitsubishi drop standard orange in favor of hai-ryokushoku for its Zero prototypes? IJN's tests of the imported He-112s coincided with the development of 12-shi. I speculate that Heinkel's RLM63 Grungrau could possibly have influenced Mitsubishi over the color scheme of 12-shi.

3.4. Conclusion

My arguments on the possible range of Zero's early overall color boil down to the following three points. First, it was glossy without any clear topcoat, and close to J3 hai-ryokushoku slightly tinted with ameiro. Second, it was not FS16350 itself, but FS16350 less aging effect. Third, it was close to, but not as dark as, RLM63 Grungrau.

In conclusion, I believe the Zero's early overall color should have been a glossy hai-ryokushoku (light greenish ash) not as dark as FS16350 or RLM63. And that color, "Zero special" as I would call it, was different from J1, a plain light gray, and slightly different from J3, which would later become IJN's standard under-surface color.

I further assess that the tone of J3 as the under-surface color varied, including less greenish and more bluish tones, and that mei-kaishoku (light ash) was sometimes field-applied over the original color on repairs and retouches.

3.5. Ameiro myth

A Japanese illustrator once highlighted the 0266's remark that the color of gen-yo Zero was like "a J3 (gray) slightly tinted with ameiro" and generalized it, without any factual grounds, into an assertion that IJN fighters had usually received a protective topcoat of clear ameiro. Over time, he has toned down his words, became shy to call it "ameiro", and eventually changed the expression to "ryoku-kasshoku (ameiro)". ("Ryoku-kasshoku" means greenish brown in Japanese.)

Shortening "mei-kaishoku tinted with ryoku-kasshoku" (light ash tinted with greenish brown) into just ryoku-kasshoku" is as incorrect and misleading as calling "hai-iro slightly tinted with ameiro" an "ameiro". It is just like calling a gull gray slightly tinted with blue as a mere "blue", or shortening duck egg green to a "duck".

The notation "ryoku-kasshoku (ameiro)" is also improper, as it gives a totally wrong impression that ryoku-kasshoku (greenish brown) is equivalent to ameiro.

Those misuses of words led to misconceptions by researchers and modelers. Quotations and references further compounded the confusions so that even some model makers and paint makers incorrectly cited "ameiro" as IJN's standard color. What a blunder!

Reisen was painted in hai-ryokushoku, not ameiro. This is the reality.


Since 1984, a Japanese researcher has repeatedly explained and illustrated in many books and magazines that Zero trainers had been painted in mei-kaishoku or "ameiro". Without checking with primary sources, some model aircraft writers regarded his assertion as a matter of course, and painted their Zero trainers as such. Not very few people have been brainwashed into believing Zero trainers had actually been painted in mei-kaishoku.

In reality, however, IJN had a principle to paint training and experimental aircraft in "tou-ou-shoku" (literally orange yellow but practically orange or mandarin orange; some people call it "ou-tou-shoku" but tou-ou-shoku is the official notation). The principle was set out in Air HQ directive #8777 of 29 December 1938 titled "Renshu-ki Kitai Gaimen Toshoku ni kansuru ken" (Re Outer Airframe Color for Trainers). The directive was reported as stating "...paint prescriptions and color samples are distributed as necessary." The "Riku-kaigun Chuo Kyotei" (Army and Navy Central Agreement) of 15 September 1942 also stated: "Training and experimental aircraft should be painted in ou-shoku [literally yellow but practically orange] wherever conditions permit." The overall orange principle remained effective until superseded by another directive of 3 July 1943. (Mr. Donald W. Thorpe touched on this July 1943 directive in his book "Japanese Naval Air Force Camouflage and Markings WWII".) Of course, no official documents show Zero trainers were painted in mei-kaishoku or hai-ryokushoku. It is barbarous and ridiculous to describe Zero trainers were painted in ameiro.

Some may argue that Zero trainers in B&W photos look similar to Zero fighters in early scheme. But that does not substantiate they actually wore the same color. Orange may as well look like light gray in B&W photos, as can be seen in the existing photos of Yokosuka K5Y Type 93 Intermediate Trainer (93-chu-ren), the biplane commonly dubbed "Aka-tombo" or red dragonfly.

I interviewed an ex-navy engineer, who had used to repair and modify aircraft at 1st Navy Aircraft Arsenal of Tsuchiura, Japan. He asserted: "Type 0 Trainer was painted in tou-oushoku, exactly the same color as used for Type 93 Aka-tombo, a reddish orange. Later, however, the topside changed to dark green." And he countered my question by asking: "Kurosu-san, is there any evidence at all that Zero trainers in mei-kaishoku ever existed?" Of course, I answered "No".

A friend of mine recently showed his 1/72 orange Zero trainer and 1/48 dark-green/orange Zero trainer at a model exhibition in Osaka. Among visitors was an old man, who used to fly Zero fighters at an IJN base in Kyusyu after finishing "Yokaren" (navy's preparatory pilot training course) in 1944. Pointing at his 1/72 orange Zero trainer, the old man said: "It reminds me of those days."

The old man recalled: "Aka-tombo, I mean 93-chu-ren, and rei-rensen (Zero trainer)... they are trainers and therefore were all painted in this color, as far as I saw them." My friend asked if he had ever seen a Zero trainer in haiiro scheme, and the old man replied:

"No, at least in Kyushu, where I stationed, I have never seen Rensen in haiiro. Well, never seen haiiro ones, but I saw, near the end of the war at Kanoya base, many machines with green paint applied over orange. Still then, the under surface was in orange."

Pointing at his 1/48 Rensen in dark-green and orange scheme, the old man continued: "Yeah, just like this. I heard that maintenance crew had painted green on them."

Development of Zero trainer began in 1942. At first, it was temporarily called "17-shi Renshu-yo Sentoki" or Type 17 Experimental Training Fighter. First prototype rolled out in January 1943, and IJN officially adopted it as A6M2-K Rei-shiki Renshu-yo Sento-ki Ichi-ichi-gata (Type 0 Training Fighter Model 11) on 17 March 1944. Between April 1943 and July 1945, 21st Navy Air Arsenal of Nagasaki and Hitachi Aircraft made 515 units.

When Zero trainer entered service in 1943, IJN was introducing, with the effect of the July 1943 directive, the two-color camouflage of topside an-ryokushoku with white-rimmed hinomaru and under surface hai-ryokushoku. Yellow IFF strips on the leading edges of inboard wings became standard then. Zero fighter's early scheme, hai-ryokushoku overall, was already obsolete then.

Early scheme Zero fighters invariably had hinomaru without white rim on the wings, although Nakajima-built machines wore white-rimmed hinomaru on the fuselage. (I suppose that aimed at easy distinction for field maintenance; Nakajima's parts were not fully compatible with Mitsubishi.) By contrast, Zero trainers, like many other navy trainers, always wore white-rimmed hinomaru on the wings and fuselage. That was because, as I suppose, hinomaru had to stand out against the background; the orange overall color needed the white rim.

Zero trainers were not gray or ameiro; they were orange!


Japanese language uses three sets of characters: Kanji or Chinese characters imported from ancient China; Hiragana phonetic letters derived from streamlined Kanji manuscripts; and Katakana phonetic letters derived from Kanji components. Most Kanji characters have two ways of pronunciation: Kun-yomi, indigenous Japanese word assigned to Kanji by its meaning; and On-yomi, adopted ancient Chinese sound.

Most color names of Kun-yomi date back to the time before Kanji were imported. Later, Kanji were assigned to those names according to the colors they meant, and On-yomi names emerged from those Kanji, chiefly for official and academic uses.

For example, iro (Kun-yomi) and shoku (On-yomi) both correspond to the Kanji shown left, and mean "color". Many color names in Japanese have a suffix iro or shoku, as in hai-iro and mei-kaishoku.

Kun-yomi names of flowers, plants, animals, and other natural elements often represent intermediate colors. For example, mizu-iro means water color, hence light blue; kitsune-iro means fox color, light brown; tsuchi-iro means earth color, dull brown; and sakura-iro means cherry color, faint pink of Japanese cherry blossom.

Another way to express intermediate colors is by compound names: combination of two elementary colors. For example, a mixture of ash (hai or kai) and green (midori or ryoku) is hai-midori-iro or hai-ryoku-shoku.

The list below shows some basic color-related Kanji images. Each image has a background of corresponding color and a description formatted as: Kun-yomi / On-yomi (English translation: practical meaning if different from literal translation) ...additional explanation.

shiro / haku (white)

kuro/ koku (black)

aka / seki (red)

daidai / tou (orange)

ki / ou, kou (yellow)

midori / ryoku (green)

ao / sei (blue)

ai / ran (indigo)

murasaki / shi (purple)

hai / kai (ash, cinder: gray)

nezumi / so (mouse, rat: gray)...not necessarily darker than hai.

cha / sa (tea: brown)

- / katsu (coarse hemp: brown)...almost interchangeable with cha; combined with shoku, katsu-shoku becomes kasshoku in liaison; much deeper than British (BS4880 / 10B-21) hemp.

The following words describe darkness (value), and sometimes chroma, of colors:

akarui / mei (light)

kurai / an (dark)

koi / nou (deep)

awai / tan (pale, faint)

A few exapmles: