In 1945 (Showa 20), American B-29 bombers stepped up their raids on the Japanese mainland. Tokyo was subjected to a massive air raid in the wee hours of the morning on March 10, as well as another one that struck its populous areas from the night of May 25 until dawn the next day.

OKI Misao, then Chief Secretary of the House of Representatives, in his Diary records the frantic efforts to extinguish the fire that broke out in the Imperial Diet building after it was hit by a bomb, as well as the experiences of Cabinet members seeking refuge in the building along with their families.

The other document shown here is a report drawn up by the U.S. 20th and 21st Bomber Commands, based in the Mariana Islands south of Japan, which carried out those bombings. The report takes note of such data as flight routes, bombing targets, and damage-assessment reports, as well as various details such as the type and tonnage of the bombs dropped. The documents from the U.S. Strategic Bomb Survey (USSBS), including the tactical mission reports, serve as important primary sources for getting a clear grasp of the actual conditions in the bombed areas at the time.