Foreign Ministry Destroyed in May 25 Air Raid

As the war turned against Japan, the Foreign Ministry began evacuating its records in 1944. In March the original treaties held in the Archives Section's record repository were moved to the basement vault of the Bank of Japan head office, and in April it was decided to send other important files to a warehouse of the Saitama Bank's Satte branch and a private storehouse in Minami-Saitama District, Saitama Prefecture. The transfers ran from 26 April to 20 May. Although most of the ministry's records were meant to go, only about 33,000 volumes were actually moved; files still being compiled and those that could be discarded stayed in the ministry. Part of the Archives Section's holdings had already been lost in a fire on 8 January 1942.

During the massive B-29 firebombing raids on Tokyo on the night of May 25, 1945, much of the Kasumigaseki government district was set ablaze. According to Japanese Wikipedia, about 498 B-29s dropped 3,262 tons of incendiaries on the Yamanote districts that night, killing 3,651 people and damaging some 165,000 houses; the Meiji Palace within the Imperial Palace grounds also burned down. The Foreign Ministry's main building was completely destroyed by fire, and approximately 20,000 volumes of irreplaceable diplomatic documents left in the building were consumed in the conflagration. A single four-story archive building, physically separated from the other structures, was the only part of the complex to survive the bombing. The ministry subsequently operated from temporary quarters, including space in other surviving government buildings, and after the war for a time in borrowed premises such as the Nissan Building.

The losses did not end there. On 7 August the ministry approved a policy of burning highly sensitive papers, and about 8,000 volumes of official documents dating from 1940 onward were destroyed in an 'emergency incineration' between 10 and 15 August. Once the occupation began, GHQ started examining the surviving records in November 1945, and by 1948 had seized 102 original treaties and agreements and a total of 1,305 volumes of files and reports, some of which were used as evidence at the International Military Tribunal for the Far East. These were returned in stages from the 1950s, though some were never recovered.

The pre-war records that survived because they had been evacuated are now kept at the Diplomatic Archives of the Ministry of Foreign Affairs, opened on 15 April 1971, and are available digitally through the Japan Center for Asian Historical Records (JACAR). The ministry's present buildings in Kasumigaseki are post-war structures: the north wing was completed in 1960 and the central and south wings in 1970.