From the introduction:
Bound by an outdated code of honor, the samurai of Kurogun struggle to balance the preservation of the small villages and towns that function as pinpricks of light in an otherwise Sunless world, by upholding their own honor and that of their family. Honor is paramount; without it, man is worth nothing and is no different from the savage beasts that roam the wilderland between settlements. And yet, the convoluted and often self-contradicting nature of honor lends to many more shades of gray than the samurai would prefer to recognize.
The dice pool mechanic (and most other game aspects) use d6, though other types of dice occasionally are used during play.