He was born as the oldest son of a retainer of the Choshu clan Genemon SATO (the ninth head of the Sato family) in current Tabuse-cho, Kumage County, Yamaguchi Prefecture.
現在の山口県熊毛郡(山口県)田布施町に長州藩武士佐藤源右衛門（佐藤家第9代当主）の長子として生まれる。