The history of an attitude. He traces half a dozen tragic heroes from their initial, meteoric success, through their downfall and honorable deaths. A perfect Aristotelian tragedy except that they don't have a tragic flaw. At least in Japanese eyes. In Japanese eyes, they fell because of their sincerity, their purity, their single-minded devotion. Aristotle might regard it as a fault -- escaping the Golden Mean, or at least not selecting the proper object of loyalty -- but in Japan, that's proof that they really are just too good for this earth.
He carefully pieces together what really is known and what is said. And what gets conveniently pared off for not matching the myth. Oddly enough, this is more for the villains of the piece than the heroes. Sometimes this is because there is less known about the heroes, which gives more flexibility, but the myth tends to shear off any of an opponent's motives for acting as they did. Yoshitsune's brother, who hunted him to his death, had reasons for his actions. Yoshitsune had a tendency to exceed orders, and he had accepted honors from the emperor without the approval of his brothers. Does this get mentioned in the legends? Even as the brother's obviously inadequate excuse? Of course not! The brother is motivated purely by spite, envy and vindictiveness. And some of his supporters get blackened as well for their part. And this happens over and over and over again.
Morris emphasizes a little too much the contrast between Western success and Japanese failure. These heroes tend to get posthumously exonerated and praised. Sugawara No Michizane -- the rare one who died in his bed -- was regarded as the author of any number of disasters that followed after his death and hit the family of his opponents. And of course, how did King Arthur end up? Or Roland? Or Robin Hood?
But the Japanese models are interesting. And the stories really are tragic, even if half (three quarters? ninety percent?) fiction.