I have been wanting to get my hands on this for a long time and it is mindblowingly cool, as I expected.
The basic deal is that the players are a bunch of ronin who have all gathered to go kill this witch O-Yanma who lives in a castle at the top of Mount Fuji, because there's a big money reward for doing it. You're basically right out of Seven Samurai.
And then you mix in a big dose of Reservoir Dogs.
First part of character generation, everyone gets dealt a secret dark fate card. These all include a good, big reason to betray at least one of the other ronin. They're also very open - each player gets to determine the story behind the fate as the game goes on.
The second big thing is Trust. All the ronin start trusting each other to varying degrees (based on their zodiac signs). Between chapters of the game, players get a chance to slowly grow their Trust for each other (or rapidly reduce it). If another ronin trusts your character, you may elect to use those points to help them in their conflicts. Or. You can use it as a bonus to yourself when your ronin is in conflict with them. Trust ends up being a huge prisoners' dilemma mechanic, as you try to give Trust to those ronin who you think (a) will help you and (b) have no reason to betray you. The brutal simplicity of the mechanic is almost sublime (I'll report on whether it actually is sublime after playing the game).
The game is actually about the ronin and their personal issues. Players may narrate new stuff into the game that is connected to their fate. As the ronin approach the witch, their fates will all be gradually revealed and the tensions in the group will be exacerbated by the Trust mechanic.
On top of all that, it's a fantastic looking book. Nice layout and fabulous spooky watercolours showing ronin and monsters and other evocative scenes (one that is particularly striking shows only a sword plunged into the snowy ground at the bottom of a steep, dark path).
Awesome stuff. Buy it. Play it.