When Goro SHIBA, a military man from Aizu and then a young boy heard of Okubo's unnatural death, he combined it with that of Takamori SAIGO and wrote, 'I am absolutely pleased that the two great men ended their lives in unnatural death, which was a natural consequence.'
会津出身の軍人である柴五郎は、当時は少年であったが、大久保の非業の死を聞いて、西郷隆盛の非業の死とあわせて「両雄非業の最期を遂げたるを当然の帰結でなりと断じて喜べり」と書いている。