Originally Posted by
fransknorge
... and then change to the Yamanote line
Yamanote line can be quite crowded. I arrived around 8:30/9:00 am at Ueno Station and it was very uncomfortable with luggage. That said, I doubt that it was more stressful than riding the Tube with luggage during morning rush hour. The trains to NRT (once you got of the local services) should be ok.