This article is for those who are visiting Japan from overseas. For a comprehensive list of the articles I have written for foreign people living or traveling in Japan, see this article.
You can readily purchase prepaid data-only SIM cards in Japan now. There are prepaid SIM card vending machines at airports. You can also choose to rent a mobile wifi router. So either way, your needs for Internet access can be met easily. If you like to live dangerously and want to make do with public wifi services, see “Public Wifi Services in Japan.”
These days, people in Japan use instant chat messaging systems for most of their messaging needs. They often come with “Internet phone call” capabilities, so that is really all you need. Line very often used for these purposes. If you can use Line and you can contact all you need to contact in Japan via Line, then you’re good to go.
However, there might be cases where you need to make and/or receive conventional phone calls, for example, i) when you have to contact with an old person, or ii) when you have to reach a old-fashioned business or public office. If you indeed have those needs, then one easy thing to do is use an good ol’ pay phone. Remember pay phones? They are still there, albeit scarcely. Finding one is going to be challenge, and you still will not have a way to receive calls.
You might think, “Well, I will just get a prepaid voice-capable SIM card then.” Unfortunately, things are not that easy here. This might be hard to understand for those coming from the US where you can easily get a prepaid cell phone at you local 7 Eleven. We have a whole lot stricter regulations here in Japan for the eligibility for cellular voice services, to prevent possible criminal activities using those services. Even if you should somehow be able to get a voice-capable SIM card, they are legally required to get your ID information (in your case, they need to see and make a copy of your passport), so you cannot just walk up to a vending machine and get a SIM card.
Narita Airports have some wifi rental and prepaid SIM card shops. I did not look through them thoroughly but only a selected few seem to offer voice-capable SIM cards in some form. SoftBank Global Rental rents out such SIM cards, which cost 110 yen (~$1USD) a day and 110 yen (~$1USD) per minute of call. JALABC rents out cell phones themselves, and depending on the plan you choose, a minute of call will cost 70 yen (~60c) to 182 yen (~$1.7USD).
If you’d like a Japan phone number with which you can receive calls, I’d recommend My 050 Service by Brastel. It will give you a phone number that starts with 050, with which you will be able to make and receive phone calls using their app on your smartphone. It will cost you nothing as long as you do not use it, and I believe (but haven’t verified) it will not cost you to receive calls at this number. There is no monthly fee, and there is no setup fee (but you may have to recharge your account for your number to be activated — you didn’t have to in the past, but I don’t know about now).
The reason I am recommending this service is that you can recharge your account at a convenience store. Credit cards can be used too, but they accept only those issued in Japan, which I am sure you have none of. There are other 050 phone number providers, for example, SMARTalk. From the feature point of view, this is a better service. Calling rates are cheaper, and it comes with a free voice mail service. But their only acceptable payment method is through Japan-issued credit cards, which is a deal breaker for you.
Note 050 numbers are not cell phone numbers. So you cannot send or receive texts at 050 numbers. In Japan, we have a phone numbering scheme which dictates what prefixes should be used for what kinds of phone numbers. Those that start with “050” are for “Internet phones,” and those that start with “090,” “080,” and “070” are for cell phones.
By the way, you will be able to keep using the 050 number even after you leave Japan, as long as you keep your account with Brastel active. This means people in Japan will be able to call you as if you were still in Japan. They will be paying only domestic calling fees and you will be paying nothing.
Another viable option if you are a Skype user is to have a Skype number, which is also a 050 number. It costs about $3 a month; you can choose to activate it only during your stay in Japan. Their rates are pretty good, even for permanent residents of Japan. And I know for a fact they accept credit cards that were issued in the US.