There's a funny part at the start of another Gibson novel where the protagonist "wishes he was back in Chiyoda", which is kind of like saying you live in Santa Clara County instead of San Jose. I guess it was harder to do research back then.
I'm not sure I get this. Chiyoda no doubt refers to the ward Chiyoda in central Tokyo, immediately to the east of Shinjuku, so would be similar to someone who used to live in San Francisco saying "I wish I was back in the Tenderloin."