![\"\"](\"\/wp-content\/uploads\/2026\/08\/PearlSpy1.jpg.jpg\")
He knew there would be no way to explain his presence if he was caught, so he remained submerged as long as he could. The tropical waters, while perfect for a casual dip, were cold enough to leach the heat from his lean, unmoving body. In the growing darkness, the sentry became increasingly difficult to see; Yoshikawa\u2019s mind began to wander. Eventually, he imagined that he could hear the sentry and heard him leave. When he finally surfaced, the sentry was<\/i> gone \u2014 but his work was done: he had thwarted Yoshikawa\u2019s reconnaissance attempt. Shivering, half drowned, and covered in scratches, the spy made his way back to the Japanese consulate in Honolulu in the dead of night, defeated.<\/p>\n\n\n\n
Or at least that was Yoshikawa\u2019s story.<\/p>\n\n\n\n
It is impossible to know what really happened, and inadvisable to take Yoshikawa\u2019s word for it. The former Imperial Japanese Navy ensign \u2014 then posing as a clerk at the consulate \u2014 was an unreliable narrator.<\/p>\n\n\n\n
Yoshikawa recalled his espionage exploits numerous times after the war \u2014 in two full-length memoirs (one published in 1963, the other in 1985), along with newspaper and magazine articles and in interviews with American and Japanese writers, reporters, and historians. At various times he recalled the same episodes differently, and in all of his accounts, <\/b>pretends to personal qualities his actions clearly belie. <\/p>\n\n\n\n
Complicating matters further, although Yoshikawa died in 1993, a Japanese publisher dealing mainly in nationalist tracts, Mainichi Ones, issued a revised version of his memoir in 2015 that made Yoshikawa\u2019s story more nationalistic and, superficially at least, more plausible. An account of the Mamala Bay excursion occurs in all Yoshikawa\u2019s full-length memoirs, richly detailed and casting him in a heroic light while explaining away his inability to obtain information on Pearl Harbor\u2019s submarine defenses \u2014 one his few failures during his mission. Some measure of skepticism is in order.<\/p>\n\n\n\n
Nonetheless it is possible, by combining what is known from American intelligence sources and Yoshikawa\u2019s own recollections, to piece together a portrait of the man and his mission. The exercise is worth the effort, because Yoshikawa was indisputably effective as a spy. His activities made a direct contribution to the Japanese victory at Pearl Harbor.<\/p>\n\n\n\n
Yoshikawa had aspired to be a naval aviator, but a debilitating stomach ailment sidelined him during training. In 1936 at age 22, fearing his career was over before it started, he gratefully accepted an offer to enter the Japanese Imperial Navy\u2019s intelligence section. He immersed himself in the study of English and read anything he could on the U.S. Navy, its warships, its bases, and its strategies and tactics. He took particular pride in his mastery of works by American naval theorist and sea power advocate Alfred Thayer Mahan, later boasting, \u201cI can still quote much of Mahan from those days.\u201d<\/p>\n\n\n\n
In 1940 the Imperial Navy charged him with his fateful mission to Pearl Harbor, which he called \u201ca half-year of furtive existence in the twilight world of the spy in which all men are enemies and fear walks always beside one.\u201d First, however, they seconded him to the foreign ministry, where he was to grow his hair out and learn the arts of diplomacy to establish his cover. The following year they sent him under official cover \u2014 as a diplomat named Tadashi Morimura \u2014 to the spacious consulate general in a quiet Honolulu neighborhood. There only the consul general, Nagao Kita, knew of Yoshikawa\u2019s true mission.<\/p>\n\n\n\n
Yoshikawa collected information anywhere he could find it. He scoured newspapers and community bulletins for scraps of useful facts. He chatted up servicemen and bought them drinks. On the pretense of taking casual strolls, he reconnoitered around military bases and Oahu\u2019s major beaches, exploring them for possible landing sites. He gathered intelligence on the depth of Kaneohe Bay and natural obstacles in the harbor by the simple expedient of taking a glass-bottomed boat tour. <\/p>\n\n\n\n
He repeatedly observed the island from the air in sightseeing trips, taking pains to bring along a different woman each time to give the impression that he was little more than a playboy with a successful MO and limited imagination. He established observation posts in secluded sugarcane fields, and in or near the establishments of friendly Japanese immigrants \u2014 the Nikkei.<\/p>\n\n\n\n
The information he collected gave attacking Japanese pilots an excellent idea of what they were up against. Detailed documents recovered from downed enemy aircraft led investigators to conclude that Japan had spies on Oahu, including \u201cpersons having no open relations with the Japanese foreign service.\u201d <\/p>\n\n\n\n
Their report made many Americans imagine a far more extensive spy network than had ever existed, and ultimately contributed to the paranoia that led to the internment of more than 120,000 Japanese and Japanese American residents from the West Coast of the continental U.S. (although, ironically, sparing those in Hawaii).<\/p>\n\n\n\n
In his postwar writings, <\/b><\/i>Yoshikawa consistently took pains to absolve the Nikkei, and especially the Nisei\u2014<\/i>the American-born offspring of Japanese immigrants\u2014of rendering him assistance. \u201cHawaii\u2019s Nisei shared a deep sense of belonging to the United States,\u201d he wrote with apparent chagrin; when entreated to do something for Japan, \u201cThey would refuse me with the line, \u2018I am an American.\u2019\u201d However, it is indisputable that without the aid\u2014witting or otherwise\u2014of some Hawaiian Nikkei, Yoshikawa would not have been nearly as successful.<\/p>\n\n\n\n
One who helped him was Taneyo Fujiwara, the proprietress of a Japanese teahouse, Shinch\u014dr\u014d, which commanded an excellent view of Pearl Harbor and was equipped with a substantial telescope. Yoshikawa used the telescope extensively, and often\u2014after feigning drunkenness\u2014spent the night unsupervised in the room where it was kept. (Interested readers can see the instrument at Shinch\u014dr\u014d\u2019s successor establishment, Natsunoya Tea House, run by Laurence Fujiwara, Taneyo\u2019s grandson.)<\/p>\n\n\n\n
Another Nikkei who assisted him was John Mikami, a taxi driver the consular staff often employed. Yoshikawa befriended and hired Mikami for frequent sightseeing trips. Though Yoshikawa never informed Mikami of his mission, the cabby seemed to have divined the purpose of Yoshikawa\u2019s excursions and went out of his way to point out details of military significance or show Yoshikawa vantage points for observing Oahu\u2019s military installations. <\/p>\n\n\n\n
Once Mikami took the spy to Schofield Barracks, command headquarters for the U.S. Army in Hawaii and home of the 25th Infantry Division. They somehow got onto the grounds and Mikami showed Yoshikawa around before heading for the exit, where he casually told the guard he had been attempting to take his fare to a tourist destination. The guard waved them on, despite the fact that Schofield is in the interior of the island far from any tourist attractions.<\/p>\n\n\n\n
At least one person offered Yoshikawa knowing aid \u2014 German spy Bernard Julius Otto K\u00fchn, whom German military intelligence had dispatched to assist the Japanese \u2014 but Yoshikawa resisted it. Under Yoshikawa\u2019s protests Nagao Kita had ordered him to meet with K\u00fchn and pay him on multiple occasions.<\/p>\n\n\n\n
Brushes with American authorities and his frequent presence near sensitive facilities notwithstanding, Yoshikawa was careful to stay on the right side of the law, or as close to it as he possibly could. \u201cEspionage essentially is at bottom an unromantic exercise in research methodology,\u201d he said. \u201cIt is all there if you will only take the trouble to dig for it.\u201d<\/p>\n\n\n\n
He dug relentlessly \u2014 but cautiously and patiently as well. He never raised the suspicions of American authorities. They never even learned his real name. The only prewar mention of Yoshikawa in military intelligence files is a routine record about his visa status under his alias. Robert L. Shivers, the FBI\u2019s man in Honolulu from August 1939 until April 1943, cultivated extensive contacts in Japan\u2019s Nikkei community. But in his memoirs he admits that he never suspected Yoshikawa.<\/p>\n\n\n\n
Yoshikawa maintained that he had no foreknowledge of the timing of the <\/b>attack on Pearl Harbor, and it is likely he did not know anything concrete. The raid\u2019s naval planners were stingy with information; even Prime Minister Hideki T\u014dj\u014d did not learn the details until after the fleet had sortied. Nevertheless, Yoshikawa certainly suspected an attack was imminent. <\/p>\n\n\n\n
In the first week of December he burned the notes, clippings, and photographs he had used to compile his reports. On December 6, Yoshikawa settled outstanding debts and treated Mikami to dinner at Shinch\u014dr\u014d. But some sensitive materials remained in the consulate\u2019s locked code room. After the attack he had to await the arrival of the consulate\u2019s cipher clerk, who had the only keys. American authorities turned up before he could burn all the evidence and caught him with a detailed, if only half-finished, hand-drawn map of Pearl Harbor. Yoshikawa\u2019s luck had run out.<\/p>\n\n\n\n In the immediate aftermath of the attack, American authorities confined the consular personnel <\/b>to the compound grounds, and quickly arrested K\u00fchn, whose extravagant spending habits had caught their attention. The German spy provided the Americans with a description of his Japanese paymaster; the Americans suspected Yoshikawa was the man. Still, considering the magnitude of the disaster they had suffered and that authorities were even then preparing to round up innocent Nikkei from the West Coast, they went remarkably easy on Yoshikawa.<\/p>\n\n\n\n Authorities eventually interned the consular staff in a comfortable \u2014 if remote \u2014 ranch in Arizona. Given the situation, their captors afforded them every courtesy; Yoshikawa and his colleagues could play tennis, use the sauna, get cocktails, and \u2014 if not for the uncertainty of the future \u2014 generally enjoy the good life. Yoshikawa found himself wondering if Americans interned in Japan would receive such treatment.<\/p>\n\n\n\n In spring 1942 (Yoshikawa believed it was May), the inevitable finally came to pass. An investigator came to question the consular staff. It soon became clear that Yoshikawa was his focus. Through four days of interrogation the spy maintained his innocence. Even when confronted with the map, he did not relent, claiming he had drawn it for the purpose of sightseeing. After the fourth day, Kita came to see him. Based on the investigator\u2019s line of questioning and on Yoshikawa\u2019s suspicious activities at the consulate, the rest of the consulate staff had concluded that he was a spy, that the Americans knew it, and that as long as he denied it they were in jeopardy. They prevailed upon Kita to ask Yoshikawa to turn himself in. Shocked, Yoshikawa said he would think about it.<\/p>\n\n\n\n But Yoshikawa had no intention of falling on his sword. \u201cMy duty ended when the bombs fell on Pearl Harbor,\u201d he explained. <\/b>\u201cAfter that it was out of my hands. I was in no hurry to die a dog\u2019s death in some ridiculous exhibition of a spirit of self-sacrifice.\u201d<\/p>\n\n\n\n This was not in line with his training. The Imperial Japanese Naval Academy had placed a premium on developing an ethic of self-sacrifice in its students \u2014 of perseverance until death. Yoshikawa instinctively recoiled from this. Despite his efforts to internalize self-denial through Buddhist meditation, he remained, in his own words, \u201cafraid to die.\u201d<\/p>\n\n\n\n Yoshikawa\u2019s resistance to indoctrination, groupthink, and the romanticization of sacrifice would later cost him his position in the navy. In the short term, however, his sense of self-preservation paid off. The next day, the interrogator told Yoshikawa that he and his colleagues were free to go. The American had had only a week to crack the case and had failed. The diplomatic corps of the United States, Japan, and Sweden had worked out an exchange of personnel; Yoshikawa and his colleagues were taken to New York in preparation for departure to Japan.<\/p>\n\n\n\n The suspicions around the spy were strong enough, however, that the authorities sought to hold Yoshikawa, and only Yoshikawa, back. The head of the Japanese diplomatic mission to the United States, Admiral Kichisabur\u014d Nomura, maintained that the full mission would return or no one would, scuttling the exchange. The Americans relented and allowed Yoshikawa to join his colleagues. He was the last to board the ship before it cast off.<\/p>\n\n\n\n At the neutral Portuguese port of Louren\u00e7o Marques in southeast Africa (present-day Maputo, Mozambique), the Japanese crossed paths with the former American mission to Japan. Yoshikawa noted that the Americans were disheveled, their bags of poor quality, and their appearances haggard. Rather than inspiring him to reflect on his own good treatment as a prisoner, the sight convinced him all the more of the necessity of struggling against the United States \u2014 which had so much power and wealth, his reasoning went, it could afford to squander it on captives. <\/p>\n\n\n\n Insight of this sort coupled with moral myopia was characteristic of Yoshikawa. While he could discern injustice and evil, it rarely truly exercised him unless it applied to him personally.<\/p>\n\n\n\n After returning to Japan in August 1942 (accounts vary as to the exact date), Yoshikawa married, began a family, and continued naval intelligence work, mainly as an analyst. Because of his skill with English, he also interrogated Allied prisoners, condemning in his memoirs the savage abuse some of them received.<\/p>\n\n\n\n Yet neither the Japanese navy nor the government officially commended him for his contributions to the success of the Pearl Harbor attack \u2014 a sore point with Yoshikawa for the rest of his life. Eventually he ran afoul of his superiors. Sometime in June 1944 Yoshikawa surmised that reports of battle successes from frontline naval units were wildly exaggerated or wholly fabricated. He produced a more modest \u2014 more accurate \u2014 estimate based on Allied media reports and intercepted radio traffic, only to have his superiors accuse him of being \u201cAmericanized\u201d and too credulous toward American propaganda.<\/p>\n\n\n\n Yoshikawa argued that if the frontline reports were accurate there would be no American warships afloat at all. But as was standard within the Imperial military at this time, politics trumped reality. Yoshikawa\u2019s estimate was discarded. The Imperial Japanese Navy would lose three fleet carriers and more than 600 aircraft during a catastrophic defeat at the June 19-20 Battle of the Philippine Sea.<\/p>\n\n\n\n Yoshikawa resigned in disgust and spent the remainder of the war working at an aircraft plant. After the surrender, he made a small fortune on the black market before receiving word that Allied war crimes investigators were seeking him and other navy colleagues on suspicion of prisoner abuse. <\/p>\n\n\n\n Believing that the United States simply sought revenge on the Japanese navy\u2019s intelligence personnel, Yoshikawa went into hiding, spending four years at two Zen Buddhist temples until the trials were over. He drifted around the country until about 1950, then returned to his family to start a new life. He opened a gas station in Shikoku, but never reconciled himself to the new Japan of the postwar era.<\/p>\n\n\n\n Shortly later, Gordon Prange, the chief historian on Gen. Douglas MacArthur\u2019s occupation staff, somehow learned of Yoshikawa\u2019s historic role and tracked him down. The former spy agreed to an interview and went to see Prange in Tokyo just before the September 1951 negotiation of the San Francisco Peace Treaty that would mark the end of the occupation. <\/p>\n\n\n\n In the early 1960s, a pair of other projects\u2014an article Yoshikawa cowrote with Marine Lt. Col. Norman Stanford, an assistant naval attach\u00e9 in Japan, for the U.S. Naval Institute\u2019s \u201cProceedings\u201d magazine and a CBS News special he cooperated with to commemorate the 20th anniversary of the attack \u2014 led many right-wing nationalists to accuse Yoshikawa of selling out to the former enemy. Postwar anti-militarism was also near its height then, leading socialists, pacifists, and much of mainstream Japan to condemn him.<\/p>\n\n\n\n Yoshikawa lived out the remainder of his life subsisting on income from the gas station, his wife\u2019s earnings as an insurance agent, and the proceeds from his memoirs and articles. He enjoyed enough esteem from his neighbors to be elected to the local town council twice. Nevertheless he became a bitter man. His memoirs are full of self-pity and bile. He faded into obscurity, a condition in which he died in 1993.<\/p>\n\n\n\n Since Takeo Yoshikawa\u2019s death, his story has taken on new life \u2014 more recently in particular. A documentary on him by Japan\u2019s national broadcaster aired in late 2014. The next year, the Mainichi Ones memoir appeared, altered to make Yoshikawa into a nationalist hero working for a righteous cause.<\/p>\n\n\n\n Yoshikawa, however, does not fill that role well. Though he displayed pride at his ability to help his country challenge the greatest power on earth, his authentic memoirs hint at doubts about the rightness of Japan\u2019s cause. He describes tears coming to his eyes upon reading Japan\u2019s declaration of war on the United States and the British Empire. But then he adds that upon rereading, he \u201ccould not help but think that it lacked a casus belli\u201d \u2014 the Anglo-American transgressions against East Asia that it cited being \u201cnothing more than backing Chiang Kai-shek.\u201d <\/p>\n\n\n\n His descriptions of captivity in American hands contain grudging acknowledgment that they treated him well. He displays something like regret about his role in making Japan\u2019s attack a success and speaks of understanding the hostility Americans hold toward him.<\/p>\n\n\n\n The Mainichi Ones memoir has eliminated much of that ambivalence. We see Yoshikawa moved to tears by the Imperial Rescript, without the later doubts. His actions become more heroic. The volume \u201ccorrects\u201d what its revisers (sometimes accurately and sometimes not) perceive to be errors in Yoshikawa\u2019s original manuscript and distorts his narrative to make Americans seem more racist than Yoshikawa had ever implied.<\/p>\n\n\n\n In his authentic 1985 memoir, Yoshikawa describes how in Hawaii no one would sell rice to the consular staff, temporarily confined to the consulate grounds, because of their perceived involvement in the Pearl Harbor attack. In the 2015 revision, no one will sell rice to \u201cJaps\u201d \u2014 an unlikely prospect on an island where one-third of the population was of Japanese descent. Elsewhere Yoshikawa tells of being escorted through New York, where passersby mumble something about \u201cJaps\u201d under their breath. In the Mainichi Ones version, these people now shout the epithet in the captives\u2019 faces.<\/p>\n\n\n\n Given that Yoshikawa changed his story and that that story has been altered since his death, there will always be some doubt about any part of it that cannot be independently corroborated. What can be said for certain is that Yoshikawa was a patriotic man from a naval background who conscientiously performed his assigned duties. Those duties, however, only helped his country commit to an ultimately disastrous course. This was something his country never let him forget during his lifetime, but now seems to be in the process of forgetting itself. <\/p>\n","protected":false},"excerpt":{"rendered":" Using simple observation, a Japanese spy in Pearl Harbor collected crucial information. His full story, however, remains hidden.<\/p>\n","protected":false},"author":7,"featured_media":110334,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"_yoast_wpseo_meta-robots-noindex":"","_yoast_wpseo_meta-robots-nofollow":"","_yoast_wpseo_canonical":"","_acf":"","_yoast_wpseo_primary_category":91,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","_smg_distribution_targets":[]},"categories":[100,91,12,25,19,70],"tags":[],"coauthors":[7365],"class_list":["post-83334","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-daily-news-roundup","category-military-history","category-news","category-newsletters","category-veterans","category-your-army"],"acf":{"subheadline":"","legacy_arc_id":"R4JORQZ26FEMHFLPAQBRSYSKDE","arc_canonical_url":"\/veterans\/military-history\/2025\/12\/07\/in-plain-sight-the-pearl-harbor-spy\/","remove_feature_photo":false,"is_sponsored":false,"subtype":"","redirect_url":"","disable_inline_ads":false,"native_logo_pretext":"Presented By:"},"yoast_head":"\n![\"\"](\"\/wp-content\/uploads\/2026\/08\/PearlSpy7.jpg.jpg\")