Not sure if Japan is an important market for IWC watches - I believe that many of the wealthier people in Japan would prefer Japanese brands such as Citizen or Seiko for obvious reasons, but given the strong purchasing power of the Japanese, there are still a number of shops selling Swiss watches incl. IWC (though there is no boutique there). Here are some photos of my journey to the nation of the rising sun -
My seat -
The journey takes around 12 hrs - need to adjust the watch in flight or before departure to avoid entering the "no adjustment zone" of 8pm - 2am (?) -
A brand-new Narita Express train takes passengers to city centre comfortably -
Ginza - the central high-end shopping district in Tokyo, similar to the Fifth Avenue in New York - 
One of the slim buildings specialises in watches -
And of course amongst those on sale, there is IWC (I hope the price tags are small enough to read as I don't want to breach forum rules)-

Time to head for another destination on Shinkansen!
Cheers,
AL