An academic research team of the Atomic Bomb Casualty Commission visited Nagasaki City on September 10, 1945. In Matsuyama-cho, Nagasaki City, the hypocenter of the bombing, dead bodies that had been exposed to the bombing were cremated and buried in the gutters of a residential area. Their white bones were scattered all over the gutter.
Immediately after the Hiroshima atomic bomb was dropped and exploded at 8:15 a.m. on August 6, 1945, a Kure Jinbu survey team investigated the city of Hiroshima on the same day. The Imperial Japanese Army Headquarters in Tokyo dispatched the General Staff Headquarters, the War Ministry, and an Army Ministry relief survey team, including Yoshio Nishina of RIKEN, to Hiroshima City on August 8. Yoshio Nishina, who was in charge of Operation No. 2, the atomic bomb development program, verified the atomic bomb, and on August 10, at a joint Army-Navy special bomb research meeting in Hijiyama-tonan, Hiroshima City, he reported, "Atomic bomb narrative recognized. The hypocenter was assumed to be about 300 meters south of Gokoku Shrine at an altitude of about 550 meters, and a survey team sent by the Agency of Technology to Hiroshima on August 8 also reported to the government and the Army and Navy in Tokyo on August 10 that it was an atomic bomb.
On August 9, 1945, at 11:02 a.m., the Nagasaki atomic bomb was dropped and exploded; at midnight on August 9, the Soviet Union entered the war, and at 10:30 p.m., the Supreme War Leadership Council was held in the Imperial Palace in Tokyo. Shortly after 11:02 p.m., the Governor of Nagasaki sent a telegram to the Western Military District General Staff announcing the dropping of a new type of bomb similar to the Hiroshima bomb on Nagasaki City. At around 11:30 a.m., the Ministry of Home Affairs or the Imperial Headquarters was informed of the new Nagasaki bomb. It was reported to the Supreme War Leadership Council of the Imperial Court, which resumed after 2:30 pm. Later, at around 2:30 a.m. on August 10, the acceptance of the Potsdam Declaration was decided at a meeting in front of the Showa Emperor.
On August 8, the War Ministry's Medical Department dispatched the Army Medical School's Hiroshima Disaster Investigation Team. On August 10, the team determined that the bomb was radioactive, based on X-ray film sensitivity. A second survey team was dispatched to Hiroshima on August 14. The second survey team was dispatched to Hiroshima on August 14, and measured radioactivity in Hiroshima City using a Lauritzen electroscope until August 17. On the morning of August 15, Yoshio Nishina announced the atomic bomb in the newspaper.
In late August and early September, the Tokyo Imperial University School of Medicine and other universities and research institutes participated in the survey and relief efforts in Hiroshima and Nagasaki. Masao Tsuzuki of the University of Tokyo, who was the leader of the Hiroshima delegation, the Army Medical Academy, and the Institute of Physical and Chemical Research participated in the investigation of Hiroshima city on August 29 as the third investigation team of the Ministry of the Army. Pathological autopsies and Geiger counters were used to investigate the effects of radiation, and on September 3, the world's first lecture on A-bomb diseases was held at the Hiroshima Prefectural Government. On August 27, Kyoto Imperial University was requested by the Commanding General of the Chinese Military District to enter the city of Hiroshima on September 2, but the investigation was abandoned when 11 people died in the Makurazaki typhoon on September 17. In Nagasaki City, Kyushu Imperial University and Kumamoto Medical College participated in the survey and relief efforts from late August to early September.
After the end of the war, the U.S. Army entered Japan, and a number of survey teams, including the Manhattan District Survey Team, which arrived at Yokohama Port on August 30, began to investigate and study the atomic bomb. On September 4, after liaison and coordination with Masao Tsuzuki, the head of the survey team at the University of Tokyo, the team entered Hiroshima City from Atsugi Air Base on September 8, and entered Nagasaki City on September 9 to begin the survey.
On September 14, 1945, the Science Research Council of Japan (the predecessor of the current Science Council of Japan) formed the Special Committee for Research on the Atomic Bomb Disaster by the Science Education Bureau of the Ministry of Education. The committee was composed of approximately 33 members, 150 researchers, and 1,500 assistants. On September 22, 1945, the U.S. General Headquarters (GHQ) formed a joint military committee to investigate the effects of the atomic bomb in Japan. The GHQ issued restrictions on speech, press, and publishing in Japan on September 19, 1945, and these restrictions remained in place until the San Francisco Peace Treaty in April 1952. (Just before that, on September 5, reporter William Burchett reported for the first time in the Daily Express that some of the damage caused by the atomic bombs had been reported overseas.) On November 30, GHQ issued a strict prohibition on the publication of atomic bomb disaster research by the Japanese, and in January 1946, the medical materials on the Hiroshima and Nagasaki atomic bombs were transferred from the Port of Kure to the Superintendent of Military Medicine in the U.S., where they were kept in secret until 1973.
