[2][3] Nihon Hidankyo is a nation-wide organisation formed by survivor groups of atomic bomb victims from Hiroshima and Nagasaki in each prefecture.

[4] The fallout from Castle Bravo, a thermonuclear weapon test conducted at Bikini Atoll by the United States in 1954, caused acute radiation syndrome in residents of neighbouring atolls and 23 crew members of the Japanese fishing vessel Daigo Fukuryū Maru.

[5] Inspired and supported by this movement, atomic bomb survivors established Nihon Hidankyo on 10 August 1956, at the second annual conference of the council in Nagasaki.

[8] In 1961, when the Soviet Union resumed nuclear tests, the communist wing of the council refused to denounce them, which led to severe internal tension.

[9] This led to a further split in the movement, with a Japan Socialist Party-backed group that denounces nuclear tests by any nation breaking away as a new council.