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Former Japan espionage officer describes regret over unused Hiroshima bomber intelligence

Ryoji Hasegawa is seen in his military uniform during World War II, in this image he provided.
Ryoji Hasegawa is seen speaking about his experiences during the war, and the intelligence the military had about U.S. bombers that would go on to drop the atomic bomb on Hiroshima, at his home in Yasu, Shiga Prefecture, on July 16, 2020. (Mainichi/Fusajiro Takada)

OSAKA -- Toward the end of World War II, on Aug. 6, 1945, Japan military intelligence had a sense that U.S. military planes, which turned out later to include one that dropped the atomic bomb on Hiroshima that day, were moving toward the country. One former soldier and member of the unit who knew about the information at the time spoke to the Mainichi Shimbun, and reflected on the regret he still feels about the choices that we made, saying, "Perhaps if we had issued an air-raid warning in Hiroshima ahead of time based on the information we'd obtained, we'd have saved lives."

    Ryoji Hasegawa, 96, lives in the city of Yasu, Shiga Prefecture, in western Japan, and formerly worked as an elementary school principal. In the last days of the war, he was a trainee officer in the special information department of the Japanese military's espionage unit, which was under the direct jurisdiction of the former Imperial army staff headquarters.

    Publicly, the special information department was known as the "Central signals inspection department," and was based in Tokyo's Suginami Ward. Among their top-secret duties were wiretapping of U.S. communications and code-breaking. Particularly, they would work out when B-29 bombers would be attacking the Japanese mainland based on their call signs.

    Around the spring of 1945, the Japanese military became aware that a U.S. forces unit referred to as V600s had been deployed to the Pacific island of Tinian. Just over 10 planes were assigned to the unit, far lower than the numbers assigned to the V400s and V500s units on the islands of Saipan and Guam, respectively. It was also understood that the planes were engaged in repeated training exercises in which they flew over waters near Japan. The aircraft's movements were taken seriously as potential evidence of the unit being entrusted with a special mission, and updates on what had been observed were regularly relayed to army staff headquarters.

    On the early morning of Aug. 6, Hasegawa was sleeping in his lodgings when he was told that, "That unit is on the move. There are concerns it may be targeting Tokyo." He went to work earlier than usual, where he soon heard, "It seems like it's headed west. The target wasn't here in Kanto." Hasegawa said he remembered feeling somewhat relieved at that moment.

    A copy of Ryoji Hasegawa's record of service in the Japanese military is seen; his work for the intelligence gathering unit is not included. (Image courtesy of Ryoji Hasegawa)

    But he said he didn't remember when he first heard that an atomic bomb had been dropped on Hiroshima, located in western Japan. He did say that just before midday, his unit commander returned with a severe expression on his face from a meeting with Imperial army staff headquarters. He was a major general who had invited Hasegawa to his home countless times, and treated him to home cooking. But after the bomb fell, he said nothing when handed a cup of tea and offered some words of consolation. Hasegawa speculated, "We didn't use the information we had on the sortie to make an effective response. Perhaps he was really affected by that feeling."

    On Aug. 9, the Soviet Union entered the Pacific War, and the U.S. military dropped a second atomic bomb on Nagasaki. With a sense that the war was lost, the special information unit began incinerating its documents on Aug. 11. Hasegawa was told to burn his code-breaking documents indoors, and he did the work caked in sweat. Similar activities took place in the military, with public documents burned. As a result, we have no idea how much information the former Japanese military had about the atomic bombers, and what measures they may have taken against them.

    On Aug. 15, after listening to Emperor Hirohito's imperial decree to end the war, the unit disbanded. Hasegawa was considering going to see Hiroshima before making his way back to his hometown of Shiga. But he gave up on the idea after mentioning it to a colleague, who said, "It's dangerous. Absolutely don't go (to Hiroshima)." After he got back to Shiga, he became a teacher at elementary and junior high schools. Even following his retirement, he would tell local students about his experiences during the war as part of their study ahead of school trips to Hiroshima.

    Hasegawa said, "Shooting down the U.S. bomber would probably have been difficult. Even so, if we used the information we had at the time to issue an air raid warning just before the bomb was dropped, perhaps we could have reduced the number of deaths among children mobilized into building removal sites and residents. That thought never leaves me."

    He went on to say, "In the autumn of 1944, when I had just enrolled at the military's signal school, one of the officers from army staff headquarters clearly said to us, 'Japan will lose this war.' Why did the fighting go on for another year? I want the handling of information at the time and the war as a whole to be scrutinized, and the results to be utilized in the way Japan advances international relations and on other fronts, without repeating the same mistakes."

    (Japanese original by Fusajiro Takada, Osaka Bureau)

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