Originally Posted by JohnWM
If you will have arrived from North America, you may be feeling somewhat grungy by that time. There are low-cost showers available, 300 Japanese yen or US$5, for 30 minutes. Liquid shampoo and soap are included in the price, as is a towel. Many here on this board forego browsing and such, and make a beeline instead towards the showers. Whatever you choose, enjoy the transit connection!
I second the shower idea. I had a 4 hour connection there a few days ago (is that too little time to head out to Narita anyone?) and took advantage of the showers. Other than that, I like to grab a quick bite and use my laptop.