Tokyo Station is located in the busy business district of Marunouchi.
It is also a major rail interchange and station serving the JR East Shinkansen (bullet trains)
Tokyo station is one of the most confusing train station in Japan, be prepared with a map if you want to move around.
(Tokyo Station Map - http://www.jreast.co.jp/e/stations/e1039.html)
Beside the many tracks and lines, there are numerous shops and restaurents inside and outside of the ticket gates.
Tokyo station has three levels or tracks floors - ground floor, basement 1 (Sobu line/Rapid, Narita Express) and basement 2 (Keiyo line/local train to Maihama, TDL). The complex has a total of over 24 tracks.
To know how to move in and out of the station - take note of the gates you want want to enter or exit.
There are more than 10 exits (ticket gate)! so be aware of where you enter or exit if you want to get back to the location you want.
Exits can be are broadly classified into two sides, Yaesu and Marunouchi(opposite sides of the station building). Exits to the east called “Yaesu ”. The exits towards the west are called “Marunouchi”. Each sides have North exit, Central exit, South exit and some others.
For all trains lines you can enter or exit Yaesu South, Yaesu Central, Yaesu North
On the Marunouchi side, there are six exits, North, Central and South at both ground and basement levels.
The station is a Major stop for The JR East and JR East-South Hokkaido Shinkansen - Tohoku, Joetsu, Hokuriku, Akita, Yamagata Shikansen (to Sendai, Shin-Aomori, Niigata, Nagano, Akita, Yamagata, Sapporo) and also the Tokaido/Sanyo Shinkansen (to Nagoya, Kyoto, Shin-Osaka, Hiroshima, Hakata)Acesss from Airports by train:
From Narita International Airport - JR Narita Express (N'Ex).
From Haneda - Monorail from terminal 1 and 2 to Hamamatsucho only and JR trains to Tokyo Station.