Twenty million people live and work in Tokyo. It's so big that nobody really knows where it stops. It's long since filled up the plain, and now it's creeping up the mountains to the west and reclaiming land from the bay in the east. The city never stops rewriting itself. In the time one street guide is produced, it's already become out of date. It's a tall city, and a deep one, as well as a spread-out one. Things are always moving below you, and above your head. All these people, flyovers, cars, walkways, subways, offices, tower blocks, power cables, pipes, apartments, it all adds up to a lot of weight. You have to do something to stop yourself caving in, or you just become a piece of flotsam or an ant in a tunnel. In smaller cities people can use the space around them to insulate themselves, to remind themselves of who they are. Not in Tokyo. You just don't have the space, not unless you're a company president, a gangster, a politician or the Emperor. You're pressed against people body to body in the trains, several hands gripping each strap on the metro trains. Apartment windows have no view but other apartment windows.