Wife and I will be flying SIN-NRT-LAX on Feb. 18. We plan to arrive at Narita on JAL #710 at 9:35 AM and depart Narita for LAX on AA #170 @ 4:10 PM. We've never visited Japan and am wondering if the seven hours we'll have between flights would be adequate to take the train from Narita to downtown Tokyo to have a look around. Could someone advise us on: 1) any formalities of leaving the airport area and then returning a few hours later, 2) cost of train to downtown (Ginza?) district and lunch including safety issues we should be aware of (we wouldn't consider using any mode of transport other than train) 3) any highlights of downtown area), 4) time we should plan to depart downtown to get back to airport with comfortable timing, and 5) anything we should definitely avoid. We're flying first on both legs and want to have time to check out the JAL and AA lounges. Any advice/suggestions will be very much appreciated.