Okubo is said to have carried around a bag which contained the letters from late Saigo even without telling his family, and the two letters were in his pocket when he was assassinated.
大久保は家族にも秘密で、生前の西郷から送られた手紙を入れた袋を持ち歩き、暗殺された時にも西郷からの手紙を2通懐に入れていたとされる。