Buaisō is the former home of post-war Japanese bureaucrat Jirō Shirasu and his wife Masako Shirasu, located in Machida, Tokyo, to the west of downtown Tokyo. The name was derived from an amalgamation of kanji for the former provinces of Musashi and Sagami, as its location is near the border between the two provinces. The house was a traditional farm house, located in what was then a rural area of Minamitama District, Tokyo.