War was over. American troops stationed in Japan soon started amateur radio using
call signs. But finaly, they were concentrated to J#$$$-types.
See http://motobayashi.net/callbook/occupied-j.html
The call areas basically comes from Japan's pre-war definition. Chosen (Korea) still used Japan's J8-prefix until Feb. 14, 1948 (then they became HL). J9 was shifted from Taiwan and Nan'yo to Okinawa.

During this era, J9AAO in Okinawa made an ultra-DX 16,800 km QSO in 6 meters, with CE1AH of Chile on October 17, 1947 [CQ].
The ITU reduced the prefix block for Japan — and Germany, too — from J to JA-JS, at Atlantic City Conference of 1947 (effective Jan. 1, 1949).
| Before the War | Atlantic City Conference | Later |
|---|---|---|
| D ... Germany | DA-DM ... Germany | DA-DR ... Germany |
| DN-DQ ... Belgian Congo | ||
| DS-DT ... (South) Korea | ||
| DR-DT ... Belorussia, USSR | ||
| DU-DZ ... Philippines | ||
| Before the War | Atlantic City Conference | Later |
| J ... Japan | JA-JS ... Japan | |
| JT-JV ... Mongolia | ||
| JW-JX ... Norway | ||
| (Not yet assigned) | JY ... Jordan | |
| (Not yet assigned) | JZ ... Netherlands New Guinea (now Indonesia) | |
So the J stations changed their call signs to JA#$$-type 2×2 format on January 1, 1949. GHQ (General Headquarters of the Allied Forces) licensed the amateur stations. Not only Americans but also a Canadian, Robert G. Robson, VE7BKA (ex VE4DO, VE1UC) in Kure was able to get his club's call sign as JA5RG. An applicant was able to get a preferable suffix reflecting his initials as requested [JE3TEA].
In Okinawa, J9, the US allocated the KR6-prefix to there where has been under American military administration, so they chanded their call sings. But the authority only premited US nationals to open amateur stations this time. Not the Japanese nationals.
In the prefix KR6, R stands for Ryukyu, the geoglaphical name of the Islands, and 6 means that here is off-shore islands from the continental W6 area (but very very far...).

Ogasawara staitions began to use KG6I$ call signs. The following call signs are reported [HG]:
KG61D ... Douglas Reef (= Okino-torishima I.) 1963 by Don Miller, W9WNV KG6IF ... Marcus I.(= Minami-torishima I.), -1965 by N7KA; 1967 by W7CB KG6IG ... Chichijima I. 1965-, by W3KTY KG6IJ ... Iwo I.
JA1EEB/KG6 has operated from Marcus I. by Mr. Tsuboi from Japan Meteorological Agency.
In June 1950, Japan enacted the current Radio Act, in which the word "Amateur Radio" was first appeared in the Japanese law history, and held the first operator examination in that month. The previous law described its station as a "Private Radio Experimental Station," having some restrictions of the output power (10W) and operating hours [JA1BC]. In such a preparation for the reopening of Japan's own amateur radio, in June 1952, American stations quickly—in about half a month—changed their call signs to use KA prefixes, which had been used as KA1 in the Philippines before the war (the A in KA suggests Asia).

They vacated the JA prefix for the Japanese licensees, while they were remaining as KA AMRS (Auxiliary Military Radio Station) about twenty years after that [JA1AN 23].
By the way, the other series of MARS in Asia existed in American phone band on 40-m. At least AI1, AI2, AI4, AI7, AJ1, AJ2, AJ4 and AJ7 might be in Japan. (The US had gotten the AA-AL block at the Atlantic City Conference of 1947 [QST].) The big differences from KA stations were that (1) they contacted only MARS having call signs of AA-AB, AH-AL and AQ-AR (but some operators sometimes responded to the state-side), and (2) they frequently used coded phrases [JA2RM 1999h2].
"MARS" uses military frequencies for military back up communications and morale use for the US Government.
"AMRS" is a method in place that allows military and US Gov civilians to operate on the Japanese Amateur radio frequencies while in Japan.
- FCC still blocks (only) KA2AA-KA9ZZ:
http://wireless.fcc.gov/services/amateur/callsigns/vanity/
- But KA0 and KA1 have been really used in Japan in our past, for Iwo Jima
and Minami-torishima, respectively.
These blocks are assignable as Group B now.
- Three two-by-three call signs ware issued in Japan:
- KA2FEC
- KA2USA
- KA2USF
Now two-by-three KAs are assignable as Group D.
These call signs above were already issued sequentially.
- The most resent QRV of an AMRS as far as my research is
JD1/KA2CC in 1988:
"KA2CC was used from Miami Torishima, JD1/M, in July 1987 and July
1988 (IARU HF Championship)"
http://www.ad1c.com/dx4win/history.htm
|
In 1952, Amateur Radio reopened in Japan, by the Japanese.
In June 1951, The authority held the first operator license exam, and in Feb. 1952, began to receive the applications for their station licenses, expecting the Peace Treaty going into effect (Apr. 28, 1952) [ZOKU]. Besides GHQ canceled the prohibition of Amateur Radio on March 11, 1952 [CQ]. and the Radio Administration Committee decided the licensing policy for Amateur Radio at the #76 Meeting on June 19, 1952 [ZOKU], and disclosed it on June 29, 1952 [JA1AN 22].
The new area definition was as the following figure and table:

| Administration Office | Call Sign |
|---|---|
| Kanto | JA1AA-JA1VZ JA1AAA-JA1VZZ |
| Shin'etsu | JA1WA-JA1ZZ JA1WAA-JA1ZZZ |
| Tokai | JA2AA-JA2VZ JA2AAA-JA2VZZ |
| Hokuriku | JA2WA-JA2ZZ JA2WAA-JA2ZZZ |
| Kinki | JA3AA-JA3ZZ JA3AAA-JA3ZZZ |
| Chugoku | JA4AA-JA4ZZ JA4AAA-JA4ZZZ |
| Shikoku | JA5AA-JA5ZZ JA5AAA-JA5ZZZ |
| Kyushu | JA6AA-JA6ZZ JA6AAA-JA6ZZZ |
| Tohoku | JA7AA-JA7ZZ JA7AAA-JA7ZZZ |
| Hokkaido | JA8AA-JA8ZZ JA8AAA-JA8ZZZ |
In this way, the Japan's authority finally issued pre-permits — for test transmissions — to thirty applicants on July 29, 1952. July 29 became the Amateur Radio Day in Japan later.
| JA1AA | Shono (ex J2IB) | JA1AB | Ichikawa | JA1AC | Murai (ex J2MI) | JA1AD | Saito (ex J2PU) |
| JA1AE | Fukushi (ex J2KM) | JA1AF | Nakayama | JA1AG | Kurokawa | JA1AH | Komiya |
| JA1AI | Inaba | JA1AJ | Taniguchi | JA1AK | Yamanaka | JA1AL | Takezawa |
| JA1WA | Abe (now JA0AA) | ||||||
| JA2AA | Nakagawa | JA2AB | Nakagawa | JA2AC | Muramatsu | JA2AD | Katayama |
| JA2WA | Kadoma (now JA9AA) | ||||||
| JA3AA | Shima | JA3AB | Fujimoto | JA3AC | Yuasa (ex J3FJ) | JA3AD | Fukada (ex J2DJ) |
| JA3AE | Takei (ex J3ES) | JA3AF | Sakurai (ex J3FZ) | ||||
| JA5AA | Kume | ||||||
| JA6AA | Itabashi | JA6AB | Kumano | JA6AC | Miyahara | ||
| JA8AA | Hama | JA8AB | Ishida |
The following five applicants of them first got the real licenses on August 27, 1952: JA1AB, JA1AF, JA1AH, JA1AJ and JA3AA [CQ][JA2RM 2001h2].
Here let's trace two pioneers' call signs. Ken'ichi Kajii became from JAZZ, 3AZ and J3CC to JA1FG; and Koichi Kasahara became from JFMT, 3AA, JXIX, J3DD, J1EZ and J2GR to JA1HAM [JA3HXJ].
From 1952 to 1954, the Shin'etsu district (current Area 0) was a part of the first call area, as well as Hokuriku (current Area 9) was the second. The reason was the authority (1) made resistance to use the numerals 1 and 0, which had not been used before the war, and (2) could not TYPE the letter "Ø." Therefore JA1WA-ZZ, WAA-WAF was issued for Shin'etsu and JA2WA-ZS for Hokuriku [OG 8481][OG 8521]. On November 27 [I need to make sure] and on December 15, 1954 for Hokuriku and Shin'etsu respectively, the authority permitted these JA1WA-ZZ, WAA-WAF and JA2WA-ZS to change to JA0AA-EF and JA9AA-DS respectively.

This re-assignment was NOT held all together in a certain day, but it ended up that all JA1WAs and JA2WAs gradually applied for their new JA0 and JA9 call signs.
JA1ZS 1954/11/26 JA1ZT 1954/12/ 2 JA1ZU 1954/12/ 2 JA1ZV 1954/12/ 2 JA1ZW 1954/10/29 JADX 1955/ 2/ 3 [Yeah! They cannot type "0"] JADY 1955/ 2/ 7 JA1ZZ 1954/12/14 JA1WAA 1954/12/17 JA1WAB 1954/12/12 JA1WAC 1954/12/17 JA1WAD 1954/12/ 4 JA1WAF 1955/ 1/11 [Probably the last JA1W] JAEI 1955/ 1/28 [First JA0] JAEJ 1955/ 2/26 JAEK 1955/ 3/ 4 JAEM 1955/ 3/ 8 JA0EN 1955/ 4/13 [First Typed "0"] JAEO 1955/ 3/ 8 |
JA2ZJ 1954/12/ 3 JA9DK 1954/12/28 [Youngest JA9] JA9DL 1955/ 3/22 JA2ZM 1954/11/29 JA2ZQ 1954/10/13 JA2ZS 1954/12/ 1 [Last JA2W] JA9DT 1954/12/11 JA9DU 1955/ 3/18 JA9DV 1954/12/11 JA9DX 1954/12/ 6 [First JA9] JA9DY 1955/ 1/25 JA9DZ 1954/12/11 JA9EA 1955/ 1/29 JA9EB 1955/ 1/10 JA9EC 1955/ 3/18 JA9ED 1955/ 3/29 JA9EE 1955/ 1/26 JA9EF 1955/ 3/24 |
After that, vacated JA1WA-ZZ, WAA-WAF and JA2WA-ZS ware recycled in the current first and second call areas. In the first (Kanto) area, the three-letter suffix call signs already existed as JA1BZ$ at the time when JA1WA-ZZ were re-issued in January and February, 1958. [CQ 1958-1] Consequently current JA1WA-ZZ stations are about four years "younger" than JA1V$s and even the beginning part of JA1AAAs. On the other hand, in the second (Tokai) area, still JA2M$s had been issued when JA9 devided. So JA2WA-ZZ were naturally re-issued after JA2VZ, around 1957. [JA2XT]
Ryukyu Government in Okinawa permitted Japanese nationals to establish amateur stations in 1961 at last. The first station by the Japanese in Okinawa was KR8AB since June 22, 1961 [CQ].

Ogasawara Is. came back to Japan on June 26, 1968. The authority allocated JD1 to here on March 6, 1969 [JA1ADN 1995].

| Administrative District |
Prefix | Islands | DXCC Country/Entity | JCG# | IOTA# | |||
|---|---|---|---|---|---|---|---|---|
| - May 29, 1976 |
May 30, 1976 - Nov. 30, 1980 |
Dec. 1, 1980 - |
||||||
| Ogasawara-vil, Tokyo-pref. |
JD1 | Nishinoshima I. | JD1(/O) | JD1(/O) | JD1(/O) | 10007 | AS-031 | |
| Ogasawara Is. aka Bonin Is. |
Mukojima Is. | |||||||
| Chichijima Is. | ||||||||
| Hahajima Is. | ||||||||
| Kazan Is. aka
Iwo Is. and Volcano Is. |
AS-030 | |||||||
| Okino-torishima I. aka
Douglas Reef and Parece Vera |
7J1 | ex AS-052 (- Feb. 1, 2001) |
||||||
| Minami-torishima I. aka
Marcus I. |
JD1(/M) | OC-073 | ||||||
Okino-torishima I. has been a separated entity (or a "country" at that time) May 30, 1976 - November 30, 1980 as 7J1. Minami-torishima I. — a separated entity since 1960 — was formerly Marcus Island. Ogasawara and Kazan Is., a separated entity since 1969, were formerly Bonin and Volcano Islands [DXCC]. KG6I, Iwo I. now belongs one of the JD1s.
But after this comeback, some Americans have operated KA stations. Following operations are reported:
KA1S 1977, Minami Torishima I. KA1AA Mar. , 1981, Minami Torishima I. KA1DX Oct. 28, 1972, Minami Torishima I. KA1MC Sept. 6, 1978, Minami Torishima I. KA2CC July 1987 and July 1988, Miami Torishima I. (at the IARU HF Championship) KA2IJ Iwo I.
Okinawa came back from the US to Japan on May 15, 1972. Existing stations KR8AA-ME changed their call signs to JR6AA-ME all together. Newly established stations after that use the JR6QUA-XZZ block followed by all of the JS6 [JA1ADN 1995].
| Okinawa-pref.
JR6AA-ME JR6QUA-XZZ JR6YAA-JR6YTJ onwards JS6AAA-JS6QQZ JS6QUA-JS6SBY onwards Same entity, included in Japan |
Ryukyu Is. | Okinawa Is. AS-017 |
Okinawa I. and Coast |
Most of the cities (Except JCC#4704, 4714);
Kunigami-gun JCG#47001, Parts of Shimaziri-gun JCG#47002 and Nakagami-gun JCG#47003 |
| Kerama Is. | Parts of Shimajiri-gun JCG#47002 | |||
| Sakishima Is. | Miyako Is. AS-079 |
Miyakojima-city JCC#4714 and
Miyako-gun JCG#47004 |
||
| Yaeyama Is. AS-024 |
Ishigaki-city JCC#4704 and
Yaeyama-gun JCG#47005 |
|||
| Senkaku Is. |
Ishigaki-city JCC#4704 | |||
| Daito Is. AS-047 |
Parts of Shimaziri-gun JCG#47002 | |||
Thus, the above historical facts made up the CURRENT Japanese call areas.

— END —
The areas where had been occupied by Japan became independent countries or returned to the original countries.
| Year | Taiwan | Guandong (Kwantung) |
Manchuria | Chosen | Nan'yo (or South Sea) | Sakhalin I. | Kril Is. |
||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Liaodong Pen. | North | South | Mariana | Palau | Caroline | Marshall | South | North | |||||
| 1854 | China | China | Chosen/ Korea |
Spain | Japan | Russia | |||||||
| 1874 | Spain | ||||||||||||
| 1875 | Russia | J7 | |||||||||||
| 1885 | Germany | ||||||||||||
| 1895.4 | J9 | Japan | China | ||||||||||
| 1895.5 | China | ||||||||||||
| 1899 | Germany | ||||||||||||
| 1905 | J8P | China | J7P | Russia | |||||||||
| 1910 | J8 | ||||||||||||
| 1919 | J9P | ||||||||||||
| 1932 | MX | ||||||||||||
| World War II | |||||||||||||
| 1945 | C3 | XU, C; C9(Manchuria) | J8 | KG6R,S,T KH0 |
KC6 | KC6 | KX6 | UA0F | UA0F | ||||
| 1948 | P5 | HM HL |
|||||||||||
| 1949 | BA-BL, BR-BT, BY-BZ |
||||||||||||
| 1950 | BM-BQ, BU-BX |
||||||||||||
| 1951 | |||||||||||||
| 1953 | |||||||||||||
| 1968 | |||||||||||||
| 1972 | |||||||||||||
| 1991 | V6 | V7 | |||||||||||
| 1994 | T8 | ||||||||||||
Where the Nan'yo (or South Sea) Islands is a mandated territory that the League of Nation gave to Japan between World Wars.
On the other hand, Japan's original areas returned after World War II by a gradual process.
| Year | Okinawa | Amami Is. |
Tokara Is. |
Ogasawara Is. |
The Four Northern Is. | |||
|---|---|---|---|---|---|---|---|---|
| Habomai Is. | Shikotan I. | Kunashiri I. | Etorofu I. | |||||
| 1854 | J5 | J1 J2 |
J7 | |||||
| 1874 | ||||||||
| 1875 | ||||||||
| 1885 | ||||||||
| 1895.4 | ||||||||
| 1895.5 | ||||||||
| 1899 | ||||||||
| 1905 | ||||||||
| 1910 | ||||||||
| 1919 | ||||||||
| 1932 | ||||||||
| World War II | ||||||||
| 1945 | J9 KR6 KR8 |
J5 JA7 KA7 |
J5 JA7 KA7 |
KG6I KA0 |
UA0F | |||
| 1948 | ||||||||
| 1949 | ||||||||
| 1950 | ||||||||
| 1951 | Japan | |||||||
| 1953 | JA6 | |||||||
| 1968 | JD1 | |||||||
| 1972 | JR6 | |||||||
| 1991 | ||||||||
| 1994 | ||||||||
The Japan-Soviet Joint Declaration of 1956 lay down that Habomai Is. and Shikotan I. should be returnable to Japan. But as a matter of fact, Russia is still the administrative authority in the Four Northern Islands.
In addition, South Korea asserted its supremacy on Takeshima Is. in Sea of Japan in 1952 and occupy since 1954. Koren operated HM9A/P (1962), 6M0DX (1998), D98TOK (1998) and D9D (2008) from there.