You should really consider flying from Narita to Osaka (KIX) and getting the Kansai Wide Pass. There are several low cost carriers leaving from Narita's new Terminal 3. This would save you from having to go from Narita into Tokyo and then doing the train to Osaka. When you arrive at KIX you can pick up the Kansai pass at the station where the train leaves for downtown Osaka. The KIX airport is lovely and light. You just walk out the front of the airport and walk directly into the station with the train. It's literally less than five minutes from the airport door to the train. You can order the pass online and they will have it ready for you when you arrive. You can use the pass while in Osaka and back and forth to Kyoto (which is only about 40 minutes away)