Tokyo Monorail
The Tokyo Monorail that runs between Haneda Airport and Tokyo, with an average interval of only 4 minutes, can take you to Hamamatsucho Station in as little as 13 minutes, where a transfer to the JR Yamanote Line can be made.
I traveled in and out of Tokyo via Haneda Airport, which is much closer than Narita. The monorail from Haneda to Hamamatsucho is super quick and convenient, and you can enjoy the scenery along the way.