Black Jack ~Blue Future~

The genius surgeon calling himself Black Jack has grown old and while his skill is sharp as ever, he's now fighting illness of his own. At times he falls into comatose state from which he won't wake up for roughly thirty hours. Yet, his unparalleled skill with a surgical knife is still in high demand. His current case leads him into dictatorship country slowly falling into ruin as its Supreme Leader is gravely ill.
[Source: MangaUpdates]