NRT is a highly slot restrictive airport that only has two runways. It has to do a lot with eminent domain problems with the farmers in the surrounding area when they first built NRT in the late 1970s.

To give you an example of how bad it is to expand NRT, there are still property owners living within NRT compounds who flat out refuse to move out.

If you look at Google Maps, you can see that there's actually several houses and farming fields right in the middle of the taxiway because some of NIMBYs just outright refuse to move out. You rarely see this as you pass by these homes because the farmers erected giant tall fences from being visible from the taxiways.

https://maps.google.com/maps?q=35.76...t=h&gl=us&z=18
http://maps.google.co.jp/maps?q=35.7...f62aad4,0&z=16
http://maps.google.co.jp/maps?q=35.7...3d9c613,0&z=19

Narita and GoJ basically has no other choice but to wait until these farmers die of old age and cross their fingers that the beneficiaries of these lands would be better people to deal (buy out) with so as to better align their taxiways and hopefully build new runways to increase capacity. As it stands now, NRT only has two runways, which is ridiculous for the needs as a gateway to Japan and Asia. Obviously, it's a no brainer that most airlines would prefer going to ICN instead as the more preferably hub and gateway to Asia.

For more history between Narita and the NIMBY farmers, watch the youtube video, or google "Sanrizuka-Shibayama United Opposition League."
http://www.youtube.com/watch?v=E6VXAb_RS2k


Simply put, NRT does not have the ability to have flights come in anytime they want. It has to be slotted. Hence, all flights from North America arrive and depart at the same time slot. Same with flights to/from Europe, etc.

If Japan were more like Communist China, they would just force the standouts out at gun point and bulldoze their homes and farmlands without pay. That would be a far simpler solution than waiting decades for this to be resolved.