One twist to be aware of - when you are flying to NRT and need connecting boarding passes, make sure you either have them with you or your itinerary printed (or on a smartphone) before you get to the international connections security checkpoint.

The UA agent in TPE was unable to print my CO BPs, and told me to get them in TPE...I forgot the CO connection counter is after security, and while NRT security agents were beyond friendly, helpful and almost fell over themselves with sorrow at my not having the BPs or a readable itinerary, I couldn't pass through without something to show them.

After trying to get on the NRT Wifi system unsuccessfully, I was able to find a copy of my receipt in email and that was enough to get me through.

Pre-boarding security was in full swing, and don't be fooled by the unlucky passenger sitting in the chair being checked - they will pull more people and send them to the corner to wait in line, so seeing that person being checked does not mean you will avoid being pulled as well.