Daigo Fukuryū Maru Aikichi Kuboyama , the boat ' s chief radioman , died less than seven months later , on 23 September 1954 , suffering from acute radiation syndrome . He is considered the first victim of the hydrogen bomb of Operation Castle Bravo . Early days . In 1947 , the fishing boat was launched from Koza , Wakayama , named . Later it became a tuna fishing boat in Yaizu , Shizuoka , where it was renamed the " Daigo Fukuryū Maru " . Nuclear test site contamination . The " Daigo Fukuryū Maru " encountered the fallout from the U . S . Castle Bravo nuclear test at Bikini Atoll , near the Marshall Islands , on 1 March 1954 . The boat , along with its 23 fishermen aboard , as well as their catch of fish , were contaminated . They returned to Yaizu , Japan on 14 March . The crew members , suffering from nausea , headaches , burns , pain in the eyes , bleeding from the gums , and other symptoms , were diagnosed with acute radiation syndrome and admitted to two Tokyo hospitals . On September 23 , chief radio operator Mr . Aikichi Kuboyama , 40 , died — the first Japanese victim of a hydrogen bomb . He left these words : " I pray that I am the last victim of an atomic or hydrogen bomb . " The sky in the west lit up like a sunrise . Eight minutes later the sound of the explosion arrived , with fallout several hours later . The fallout , fine white flaky dust of calcinated Bikini Island coral , had absorbed highly radioactive fission product s , and fell on the ship for three hours . The fishermen scooped it into bags with their bare hands . With one fisherman , Matashichi Oishi , reporting that he " took a lick " of the dust that fell on his ship , describing it as gritty but with no taste . The dust stuck to surfaces , bodies and hair ; after the radiation sickness symptoms appeared , the fishermen called it . The US government refused to disclose the fallout ' s composition due to " national security " , as the isotopic ratios , namely a percentage of uranium - 237 , could , through a radio - chemical analysis of the fallout , reveal the nature of the device to the Soviet Union , which had , as of 1954 not been successful with thermonuclear staging . Lewis Strauss , the head of the AEC , issued a series of denials ; he also hypothesized that the lesions on the fishermen ' s bodies were not caused by radiation but by the chemical action of the caustic burnt lime that is produced when coral is calcined , that they were inside the danger zone ( while they were 40 miles away ) , and told President Eisenhower ' s press secretary that the " Lucky Dragon # 5 " may have been a " Red spy outfit " , commanded by a Soviet agent intentionally exposing the ship ' s crew and catch to embarrass the USA and gain intelligence on the tests device . He also denied the extent of the claimed contamination of the fish caught by " Daigo Fukuryu Maru " and other ships . The FDA however later imposed rigid restrictions on tuna imports . The United States dispatched two medical scientists to Japan to study the effects of fallout on the ship ' s crew and to assist their doctors . Publications of the fallout analysis was a militarily sensitive issue , with Joseph Rotblat deducing the staging nature of the Castle Bravo device by studying the ratio and presence of tell - tale isotopes present in the fallout . With this information having a history of being regarded as potentially revealing the means by which megaton yield nuclear devices achieve their yield . When the test was held , the " Daigo Fukuryū Maru " was catching fish outside the danger zone which the U . S . government had declared in advance . However , the test was over twice as powerful as it was predicted to be , and changes in weather patterns blew nuclear fallout , in the form of a fine ash , outside of the danger zone . The fishermen realized the danger , and attempted to escape from the area , but they took time to retrieve fishing gear from the sea , exposing themselves to radioactive fallout for several hours . Later , the United States expanded the danger zone and it was revealed that in addition to the " Daigo Fukuryū Maru " , many other fishing boats were in the expanded zone at the time . It is estimated that about one - hundred fishing boats were contaminated to some degree by fallout from the test . Many hundreds of inhabitants of the Marshall Islands were also exposed , and a number of islands had to be evacuated entirely . After " Daigo Fukuryū Maru " returned to its homeport of Yaizu , Shizuoka on 14 March 1954 , Japanese biophysicist Yasushi Nishiwaki immediately traveled from Osaka to Yaizu to examine the crew and their boat . He quickly concluded that they had been exposed to radioactive fallout and wrote a letter to the chief of the United States Atomic Energy Commission asking for more information on how to treat the crew . The US did not respond to Nishiwaki ' s letter or to letters from other Japanese scientists requesting information and help . The US at first tried to cover up the " Lucky Dragon " incident , sequestering the victims and declaring them off limits . Later the United States paid Kuboyama ' s widow and children the equivalent in yen of about $ 2 , 500 ( $ in 2018 ) . The tragedy of the " Daigo Fukuryū Maru " gave rise to a fierce anti - nuclear movement in Japan , rising especially from the fear that the contaminated fish had entered the market . The U . S . government feared this movement would lead to an anti - American movement , and attempted to quickly negotiate a settlement with the Japanese government ( led at the time by the Prime Minister Shigeru Yoshida , who was considered to be a pro - U . S . politician ) . The Japanese and U . S . governments reached a compensation settlement , with the transfer to Japan of a compensation of US $ 15 , 300 , 000 , of which it is reported that the fishery received a compensation of US $ 2 million , with the surviving crew receiving about ¥ 2 million each , ( $ 5 , 550 in 1954 , $ in 2018 ) . It was also agreed that the victims would not be given Hibakusha status . The Japanese government also acknowledged that it would not pursue further reparations from the U . S . government . The " Daigo Fukuryū Maru " was preserved in 1976 and is now on display in Tokyo at the Tokyo Metropolitan Daigo Fukuryū Maru Exhibition Hall . Film version . A film version of the events , " Daigo Fukuryū Maru " , was made in 1959 , directed and screenwritten by Kaneto Shindo , and produced by Kindai Eiga Kyokai and " Shin Seiki Eiga " .