The Hagakure is the book of the Samurai, written at a time when the traditional way was in decline. In a series of short passages it attempts to communicate the spirit of the old warrior caste, define exactly what it means to be a samurai and to act as a manual for all who seek to follow that path.
The way is one primarily of death, and the sincerity that is presumed to go with it. A samurai devotes himself entirely to the service of his master, and so lays down his life not once, but every moment of every day, until death completes his duty. The complete subjugation of personal desire frees them to pursue the lives most helpful to their lords, and of the fear of death, to die is their purpose, one should never fear the completion of a task of work. The simplicity of the ideology is attractive, despite everything, life has a clear purpose and death is something to be embraced, though not sought out, the man you serve is the one you love the most. All our questions and nagging everyday conflicts are answered, perhaps not to our satisfaction, but answered all the same.
I’d say it’s definitely worth reading, the same way a radio transmission from a planet light years away would be worth listening to. The ideas in it seem alien to us now, so removed from our thinking by time and cultural upheaval, perhaps distance too, I’m not entirely sure how different Japan is from the west. Read it through and then try to imagine a world where people thought like that, an entire empire run according to these principles. Ask yourself how and why such a world was flawed, if you believe it to be, and in what ways it might have been superior to our own. Do you find the path in any way appealing?