Narita is Japan's main international airport similar to JFK for New York, Heathrow in London or even Charles de Gaul to Paris. The main difference is that it's actually 80km's from central Tokyo and only has two runways, one of which requires a taxi time of some twenty five minutes (before queues). Having recently travelled again outside Japan I was reminded how painful it is to get there and back and am always left with a feeling that it should be closed and relocated somewhere passengers would actually like to fly from.
There are various options for getting there. The Narita Express is a dedicated train however is limited to speeds so as not to compete with the bus service. It also starts late and finishes early so not the best option if you're taking a red eye flight. There are high speed trains but these depart from Nippori, an area of Tokyo that is almost as difficult to get to as the airport itself. There are also the limousine buses (a coach to you or I) that depart from most of the main hotels across the city however these run the risk of being caught in flight missing traffic jams.
And then there is Haneda in downtown Tokyo. For years this was limited to a single international flight to Hawaii but not anymore. A new international terminal and an expanding list of carriers and destinations is beginning to provide a real alternative to the ageing Narita. Even though many of the flights are early morning or late at night, it's easy. And a new line has just been announced that will cut the time from Tokyo station to a very amenable eighteen minutes. I like Haneda. I dread Narita.