Originally Posted by
shuigao
Pretty much all of the top restaurants (if you're planning to visit) need advance reservations.
JR Pass (the nationwide one) must be bought outside of Japan.
If you're planning to rent a pocket wifi, for many providers you need to arrange at least a few days before the trip (they mail the wifi router thing to the airport post office).
Does NRT have any mobile kiosks that rent mobile wifi routers on the spot without needing a reservation? I've seen them at Haneda but it's been a few years since I've flown into NRT and they didn't have them in the past, at least none that I remember seeing.