Also if you've got status with an airline (i.e. UA Gold) or are flying back in J, please oh please check out the NH lounge at NRT. Easily one of the best lounges in Asia on shower quality alone (i.e. squeaky clean and loaded with amenities). They've also got a sushi and ramen bar and a buffet that makes the UC look like the appetizer station at a Ponderosa. The booze ain't bad either
Finally, if that wasn't enough to convince you, they also have a sleeping section with blackout curtain and massage chairs that will whisk you to sleep.There are other lounges at NRT you would also have access to like the UC (which some FTers report have slightly better water pressure than the NH club but I'd argue the cleanliness and amenities alone make it way better than the UC).
I should also mention that while you're in Tokyo, make sure you check out the fish market and more specifically the sushi vendors in that area. They open as early as 5 AM and the experience is well worth the cost of admission!
Safe Travels,
James