Yoshikawa file photo [8572]

Takeo Yoshikawa

Given NameTakeo


ww2dbaseTakeo Yoshikawa was born in Shikoku, Japan to a policeman. He graduated from the Japanese Naval Academy at Etajima in 1933 at the top of his class. In the 1920s, he served aboard the armored cruiser Asama and later as a submariner. In 1934, he began training as a pilot, but a severe stomach ailment prevented him from completing the training program. In 1936, he was discharged from the Japanese Navy due to health reasons, and he contemplated suicide for the disgrace. In 1937, he returned to the Japanese Navy, this time as an intelligence officer with the United States and United Kingdom section. His detection of a plain-language shortwave radio transmission noting that 17 British transports near the Crown Colony of Freetown in Western Africa directly led to the German sinking of several of these transports, and for this he received a personal letter of appreciation from Adolf Hitler.

ww2dbaseIn 1940, Ensign Yoshikawa became a junior diplomat after passing the Foreign Ministry English examinations. With this new credential and with the false identity of Tadashi Morimura, he sailed with Japanese Consul-General Nagao Kita on 27 Mar 1941 for the United States aboard the liner Nitta Maru. He rented a second story apartment in Hawaii, United States that overlooked Pearl Harbor. He provided intelligence to the Japanese Navy by taking photographs of ships, recording ship movements, studying American military base security measures, observing bases from the sky in rented small planes, and studying harbor floor by glass-bottomed tourist boats and by diving with hollow reeds as breathing devices. Many of his observations made on foot were done from a teahouse at Aiea Heights and the Shuncho ro restaurant (a geisha house) on Makanani Drive, both of which provided excellent view of the harbor. Although Hawaii had a large population of people with Japanese ancestry, Yoshikawa never made use of this potential resource; he believed that the Japanese-Americans could not be trusted because most of them were loyal to the United States. The intelligence he attained was sent to Tokyo in the PURPLE code used by the Japanese Foreign Ministry, which had been cracked by the Americans, but his messages were never discovered by the United States because messages sent from the consulate in Hawaii was considered very low priority, as most messages were commercial in nature. His report of the double-row typical mooring pattern of American battleships and the usual lack of aircraft patrols to the north of Oahu, Hawaii were both critical in the subsequent attack plans.

ww2dbaseWhen he heard the secret message "east wind, rain" over shortwave radio from Tokyo, which signaled imminent attack, Yoshikawa destroyed all evidence of his espionage activities. On 5 Dec, two days before the attack, he received a direct message asking him whether the American ships were protected by anti-aircraft weapons or anti-submarine nets; his response could have tipped off the Americans about the upcoming attack, but that message was not discovered and decrypted until the day after the attack. Immediately after the attack, when the United States Federal Bureau of Investigation approached him, FBI agents found no signs of foul play. Between Dec 1941 and Mar 1942, he was kept under watch in San Diego, California, United States. Between Mar and Aug, he was placed in a camp in Arizona, United States. He returned to Japan in Aug 1942 in a diplomat prisoner exchange.

ww2dbaseDue to the sensitive nature of his work, Yoshikawa never received recognition for his significant contribution to the Japanese success at Pearl Harbor during the war, though he continued to work for Japanese Navy intelligence. After the war, fearful of American retribution, he went into hiding as a Buddhist monk, returning to his wife and two children only after the American occupation ended in 1952. In 1955, he opened a candy business. In 1960, he told his story to an American audience, and after which he became a scape goat for Japan's participation in the Pacific War. As a result, his business soon failed. Unable to obtain any job, he remained unemployed for the remainder of his life, supported by his wife who was an insurance saleswoman. He was reportedly bitter at everyone except for his family. "My wife alone shows me great respect," he later said. "Every day she bows to me. She knows I am a man of history." He passed away in 1993.

ww2dbaseSources: HistoryNet, Japanese Intelligence in World War II, Wikipedia.

Last Major Revision: Dec 2009

Takeo Yoshikawa Interactive Map

Takeo Yoshikawa Timeline

1 Jan 1914 Takeo Yoshikawa was born.
27 Mar 1941 Japanese spy Takeo Yoshikawa arrived at the US Territory of Hawaii aboard the passenger liner Nitta Maru, under the guise of a diplomat.
6 Dec 1941 Japanese spy Yoshikawa reported US ship locations in Pearl Harbor; the message was decrypted aboard Japanese carrier Akagi 36 minutes later.

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Visitor Submitted Comments

1. Rob Stuart says:
8 Dec 2009 05:57:19 PM

This is an interesting item but it seems to include some inaccurate information. For example, it is not true that Yoshikawa’s reports to Tokyo were sent in the Purple cipher. The Honolulu consulate did not even have a Purple machine. According to At Dawn We Slept, his reports were sent in the code known to the US as J-19 until 2 December 1941, when Tokyo ordered the consulate to burn its copies. From then until 7 December the code dubbed PA-K2 was used.

This profile also says that Yoshikawa “heard the secret message "east wind, rain" over shortwave radio from Tokyo”. It’s almost certain that this message was in fact never sent.

I am also suspicious of the statement about Yoshikawa’s supposed “detection of a plain-language shortwave radio transmission noting that 17 British transports near the Crown Colony of Freetown in Western Africa directly led to the German sinking of several of these transports, and for this he received a personal letter of appreciation from Adolf Hitler”. This is very vague but possibly refers to convoy SLS 64, which left Freetown with 19 ships on 30 January 1941, en route to the UK. The German cruiser Hipper attacked it on 12 February, sinking seven ships. So far, so good, but there seems to be no indication in any reputable source that the Hipper found the convoy on the basis of SIGINT. Is there any actual evidence to support Yoshikawa’s story?

2. Anonymous🙀 says:
16 Feb 2016 08:27:15 AM

Wow cool
3. Milt Morris says:
27 Mar 2020 05:02:31 PM

The consulate in Honolulu may not have been decrypting messages. But America's two may decryption posts during that era were in Honolulu & the Philippines. An admission that America broke the Japanese Naval Code prior to Pearl Harbor would be an everlasting embarrassment. But our government admits that it has broken the code less than 6 mos. after Pearl Harbor.

Many now think that America knew in advance of the attack on Pearl Harbor, but did nothing to prevent it.

Pearl Harbor was the backdoor into the European war.

4. r thornton says:
28 Mar 2020 06:56:23 AM

Both the FDI and the USNavy were actively surveilling members of the Japanese consulate in Honolulu. It is highly unlikely that Yoshikawa escaped their attention.
5. Commenter identity confirmed David Stubblebine says:
28 Mar 2020 11:46:12 AM

Milt Morris (#3 above):
To say “Many now think that America knew in advance of the attack on Pearl Harbor” is correct in that many people think it, but all of them are wrong. This has been categorically debunked several times over but the unfounded belief lives on somehow. The article you referenced starts from the position that America bungled Pearl Harbor and then sets out to prove that very point. This is circular logic and proves nothing. Further, the second comment under that article (posted 6 years ago) thoroughly and factually debunks it. To say, “Pearl Harbor was the backdoor into the European war” is true in the sense that is how it worked out but the idea that America intentionally sacrificed the men at Pearl Harbor just to get into the war in Europe is absurd.

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