Cheap SIM cards and low-cost smartphones that can be used without credit cards

LINEMO is a low-cost SIM card provided by SoftBank (online contract only). In addition to the low monthly fee, the communication charges for chatting, voice calls, and video calls using the "LINE app" are free*. Those who mainly communicate with LINE and do not use voice calls are suitable for this service.
There are two plans: the "Mini Plan (3GB + free LINE)" with a basic monthly charge of 990 yen (including tax) and the "Smartphone Plan (20GB + free LINE)" with 2,728 yen (including tax). They charge neither contract administration fee nor cancellation fee. The communication line is the same as SoftBank with standard 5G communication.
The payment method is credit cards or bank account transfers. Since it is possible to transfer from a Japanese bank account, those who do not have a credit card issued in Japan can also sign up for the service. Besides, there are various options such as flat-rate calling, bring-your-own-device warranty, international roaming, and international calling. Therefore, you can use it as-is during overseas business trips or temporarily return. LINEMO is recommendable for the following people; not having a Japanese credit card, using LINE frequently, or attempting to save communication costs in Japan.
*: except location sharing, LINE LIVE, the stamp shop, and reading news articles

ahamo is a low-cost SIM card and smartphone provided by NTT DOCOMO. It is possible to subscribe only online. You can complete all procedures, including contract application and support, online. There are no contract cancellation fees or minimum usage period. Therefore, it is recommendable for those who stay in Japan for a short period.
Remarkably, all price plans have a service that allows free domestic calls of up to 5 minutes. If you make many short calls, such as restaurant/hotel reservations, contact companies, and small inquiries, ahamo is recommendable. There is no limitation on the number of calls. If you call for over 5 minutes, they charge 22 yen per 30 seconds (tax included).
There are two price plans: the 20GB Plan (20GB + free domestic calls within 5 minutes) with a monthly fee of 2,970 yen (including tax) and the 100GB Plan (100GB + free domestic calls within 5 minutes) with a monthly of 4,950 yen (including tax). The 100GB plan, which no other low-cost SIM card or smartphone offers, allows for approximately 85 hours of video viewing and 170 hours of online meeting. It satisfies even heavy internet users.
You can select to pay by credit card or Japanese bank account transfer when you contract. If you are already under contract, you can change it after logging in to the website. In addition, overseas roaming, used in 82 countries, is available with no application and no additional charge. To use it, turn on the data roaming setting on your phone. Even though you can use it with a simple process, the monthly data capacity is 20GB. ahamo is especially recommendable for those who regularly return home temporarily or frequently travel overseas on business trips.

Both data-only SIM cards and data+voice call SIM cards can be paid by account transfer in OCN Mobile ONE. You cannot choose account tranfer in the website so you have to call customer center (0120-506-506, open at 10am-7pm on weekday) to ask sending a document for account transfer after applying cheap SIM card or low-cost smartphone via Internet. You can use account transfer by filling out the form and return it by mail. Before completing account transfer setting, you have to pay charge at convenience store. Also, OCN Mobile ONE provides special SIM card, which count data communication on daily so this operator is recommended especially for who use data communication stable.

You switch from another company's SIM cards, the monthly usage fee can be paid by account transfer. (*NOTICE:The service will be applied only if you switch from another company's SIM cards. Also, if you contract newly, you need credit cards.) Most of cheap SIM cards and low-cost smartphones costs tranfer fee 110yen to 220yen, but UQ Mobile do not charge it. Also, both data-only SIM cards and data+voice call SIM cards are enable to use account transfer. You have to remind that they need 1 or 2 months to complete setting account transfer so that you have to use convenience store payment untill the setting end. If you want to pay for low-cost smartphone, you can also use cash-on-delivery. (*NOTICE: you have to pay COD fee) UQ Mobile has been awarded by the best high-speed signaling cheap SIM card two times in a research instituted by third-party organisation. And, they have an excellent reputation for high quality and signaling rate. We recommend this cheap SIM cards and low-cost smartphones especially for those who want to be particular about the signaling speed and quality of communication line.

All of plans can be paid by credit card, account transfer, Rakuten Super Point and debit card*. But you have to remind if you choose account transfer, you have to pay low-cost smartphone's charge by cash-on-delivery or Rakuten Super Point so you have to pay phone expences by two way every month. Please be careful of Rakuten Super Point maximum payment is 30,000yen. Rakuten Mobile accepts all services request via Internet, like applying cheap SIM cards or low-cost smartphones, and request account transfer, so it is easy to use.
*Only Rakuten Bank Debit Card or Suruga Bank Debit Card