ORDER. I placed an order for the Premium WiFi on their website (paid online and indicated Narita Airport Terminal 2 post office as the pick-up location) five days before my scheduled arrival. I received an email confirmation two days later, and the day after that the tracking number which I would need to show to the post office.
PRICE. My 17-day rental for the Japan Wireless Premium WiFi cost me 9280 yen, plus 500 yen for shipping. An average of 575 yen (about Php 270) per day. This is the average rate for rentals of 15 days or more (it would cost a bit more for shorter rental periods).
PICKUP. The Narita Airport Terminal 2 Post Office, located on the 3rd floor (Arrivals area), is open daily from 830am to 8pm. Pickup was smooth and quick. I just gave them the tracking number and showed them my passport, and they gave me my parcel. Inside the parcel was a return envelope, and a black pouch containing the router, cable, AC adapter, and powerbank.
USE. On the router is a sticker with the router name and password. Turn it on and connect. I was on the go for a minimum of 12 hours every day and never did the battery die on me. Two devices (three to four devices when my friends joined me during the second half on the trip) were connected to the router, though not in use every minute, and the router battery would still be around 20% when we got back to the hotel to call it a day. My phone's battery drains quickly and the powerbank was its lifesaver.
COVERAGE. The Premium WiFi according to the website would have 100% area coverage, but I found this is not so—I had no connection when I went hiking in Senjogahara Marshlands in Nikko and in Aokigahara in Yamanashi. Not really a problem as I was in the woods to hike, not to while away time on social media.
RETURN. Return was easy. Just put everything inside the return envelope and drop it off at any post box. For Narita Airport Terminal 2, my airport of departure, there are three post boxes on the 3rd floor (Departure floor, before entering the Security Check/Immigration) and one post box on the 1st floor (Arrival floor).
If I travel to Japan again for 15 days or more, I would definitely rent the pocket WiFi from Japan Wireless again. And no, this is not a sponsored post.