Where can I find Kato imported model sets?

The best sources for imported Kato models that I have found are:

For trains: Brooklyn Locomotive Works

For track: Toy Train Heaven Of these two, Toy Train Heaven has the larger selection of buildings.

Another source for trains is

For the best selection of Kato, Tomix, Green Max, MicroAce and other Japan manufacturers, you should try one of the online Japanese train stores. My favorites are:

Rainbow Ten

Hobby Search Prices from these sites, with shipping, are comparible to US prices, and they both take MasterCard and Visa. And the package is delivered in less than a week, frequently quicker than orders from US train hobby shops. You can also get new releases months before they appear in the US, assuming they are released the US.