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From what I've read, Clavell's portrayal of the Samurai culture in Japan is not too far from the reality.
For example, this guidance from Uesugi Kenshin (1530-1578):
Fate is in Heaven, the armour is on the breast, success is with the legs. Go to the battlefield firmly confident of victory, and you will come home with no wounds whatever. Engage in combat fully determined to die and you will be alive; wish to survive in the battle and you will surely meet death. When you leave the house determined not to see it again you will come home safely; when you have any thought of returning you will not return. You may not be in the wrong to think that the world is always subject to change, but the warrior must not entertain this way of thinking, for his fate is always determined.
I'd say that, to modern eyes, that would appear as "authoritarian and death-obsessed".
As for the fatalistic approach of the Samurai, in The Making of Modern Japan, Marius Jansen observes that:
The Samurai was supposed to have a fatalistic preparedness to redeem his name and honour by the excruciatingly painful self-immolation of seppuku or, more vulgarly, "hara-kiri" to which his lord might sentence him.
Failure to carry out the order would result in the loss of name and honor, not just for the Samurai, but also for his family.
The early seventeenth-century primer of Samurai morality, Hagakure, by Yamamoto Tsunetomo provides an excellent introduction to the Samurai value system.