Myself is a Japanese, and resident of Japan. You can not use my way – post paid SIM & optical internet line.
Use your unlocked phone with SIMs
1) Your carrier’s roaming service
At first, please check the price of your carrier’s roaming service.
2) Prepaid Japanese SIMs
If you prefer Japanese Prepaid SIMs, most of the international airports have auto-venders of Prepaid SIMs, served by MVNO, and the lines are mostly served by NTT docomo. I am using “mineo” line of MVNO.
Find automatic venders
When you see telecommunication companies in the airport terminal, they are mostly settled on Departure level, it is for the service for Japanese who are going to abroad. Search Arrival level finding auto venders.
NTT Communication is also a MVNO, this shot is taken in Narita airport.
Seems you can use credit card, but when it is a debt card, I am not so much sure whether it accepts.
Or you can buy prepaid Japanese SIM in kkday too. You can pick up in Japanese some airports, OOPS! one of the main airports of mine is not including 😀
Preserve in KKday
If you want to preserve, you can buy through KKday.
KKday Japan Prepaid 4G SIM Card
Seems this SIM is also provided by MVNO, and the network is NTTDocomo.
In this plan, you can choose “1GB 6-Day Data Plan Package”, less than US$10. It can be the most cheap, as I know.
Indeed as of April 2018, if your arrival is Fukuoka airport or Naha airport, you can not pickup this SIM. Please try to find automatic venders.
3) AIS SIM2Fly
Here is another prepaid SIM what are roaming Thai SIM, AIS’s SIM2Fly, what is for round Asia SIM, if you are traveling round Asia, it can be super useful.
I often use this SIM while traveling Asia, and 3GB/ 8days is too much for my use, I keep using this SIM in Japan too. The network is SoftBank.
See also: AIS SIM2Fly
Rent Pocket Wifi
If you have locked smart phones only, you can also rent a pocket WiFi in the airports too.
You can pre-order in kkday too. Guess preserve/ preorder can be cheaper than renting on the counter.
The good point is you can rent in Fukuoka airport or Naha airport where you can not pickup KKday’s SIM.
KKday Japan Unlimited 4G Portable Wi-Fi Rental
The point is the network of this WiFi is Softbank.
If you prefer NTT Docomo (in my opinion, if you are climbing mountains or going to rural area, I recommend to use docomo’s line.
KKday Japan Docomo 4G/LTE/3G Portable Wi-Fi Rental