At the beginning of book 6, it makes a big deal about making the party have to "infiltrate" Kasai, about how all the gates are guarded, the difficulties of trying to fly over the walls, etc. However, when I look at the map of Kasai in the gazetteer, I don't see any signs of walls or gates. What's more the city has a very long waterfront, and it seems like it would be easy-peasy for anyone to get into the city, let alone high-level magic-capable PCs. (Also, having the palace complex at the very edge of town seems like bad design, from a defense point of view. I wouldn't be surprised if my party just decided to blast into the palace first thing, bypassing all the rest of the city.)
I know there are ways to work around this, but I'm just curious how other DMs handled this part of the adventure. I know if I tell my party they have to "sneak" into town, they're going to want all kinds of details about the city's layout, defenses, etc. and then will come up with some improbable strategy I'd never have dreamed of.
True, Kasai lacks walls, except around the Imperial Palace. Instead, it has canals that act as moats. I guess the bridges are guarded. A good swim check and stealth check would be enough to sneak in.
Nevertheless, the party in my campaign received a good description of Kasai from many people who had visited there, teleported to an alley next to a good inn from the deck of a ship, and rented a room there.
They had good information about the rules of imperial succession from a befriended local governor, so they visited the island of the Imperial Shrine before visiting the city itself. Thus, they did not need to infiltrate Kasai to scout out the enemy or learn the succession rules. Instead, they wanted the room at the inn as a staging area for their surprise visit to the Imperial Palace the next day.
They had deduced one key factor that derailed many details of both Tide of Honor and The Empty Throne: they did not need to lead a rebellion. They had Ameiko Amatatsu and Amaya Amatatsu, the only two true heirs to the Jade Throne. After Amaya gained official acknowledgement of her heritage and took the throne, the Minkaian reverence for tradition would make almost everyone else fall in line. (Ameiko decided that the role of leader of the far-traveling Amatatsu family would be more fun, once they adopted more people into the clan.)
Furthermore, the party had made a secret deal with Renshii Meida in advance (they had really good information! They earned that information through good roleplaying) for her to support them in exchange for her relatives being declared the new Sugimatu family. Meida made sure that her beloved Soro Takahiro, the Jade Regent, was out of Kasai that day.