Tired of Expensive Monthly Mobile Bills in Japan? Check Out this Cheap and Cheerful Option!

  • HOW TO
  • Nowadays, almost everywhere in the world children, teenagers, and adults own their own mobile phones so that they can stay connected every day for either work or social purposes. This is no different in Japan, however, one of the downsides of having a mobile phone in Japan is that it can be expensive. If you’re here on a long-term overseas experience, then a great way to cut the costs of owning a mobile phone is by purchasing a ‘kakuyasu sim’.

    What is a kakuyasu sim?

    “Kakuyasu” means “cheap” and what makes the kakuyasu sim cards cheap is because the service uses the Mobile Virtual Network Operator (MVNO). Kakuyasu sim providers do not own the wireless network but instead, have a contract with the network provider to use their services. Currently, the only networks that can be used with the kakuyasu sim in Japan are NTT Docomo and AU.

    Kakuyasu sim service vs standard network provider service

    If you’re already living in Japan then you may already be well aware that the monthly mobile costs are high in comparison to other countries. Monthly costs are generally around 6,000 yen and above, with some network providers including additional costs depending on the mobile handset selected, and whether you require data to be added.

    With the kakuyasu sim service, you have the choice between a data or a voice sim where no number is provided for the data-only sim, and the voice sim card comes with a 070, 080 or 090 phone number. However, if you already have a Japanese mobile number with another network provider, you can also get it changed with the My Number Portability (MNP) service so that it can be used with the kakuyasu sim service.

    One main difference with the kakuyasu sim service is that it doesn’t come with an e-mail address like standard network providers so you’ll have to use a different one like a Japanese yahoo e-mail address, and so on. It also doesn’t provide an unlimited call service (kakehoudai) either.

    Kakuyasu sim providers also have smartphone sets available where you can purchase an unlocked mobile handset from the selection they have on offer and opt for it to include a data or voice sim. Even though there is only a limited range of handsets available, you can use any unlocked phone if you already have one or you can even purchase one beforehand.

    How much is it?

    The monthly price varies depending on whether you opt for a data-only sim, a voice sim, or the smartphone set, and obviously depends on the amount of data you use or calls you make within the month. Most kakuyasu sim providers charge customers an average of 900 yen for 1GB, 1500 yen for 5GB, 2500 yen for 10GB, and 2900 yen for unlimited LTE usage on the data sim plus an extra 700-900 yen if you would like voice services as well. Most kakuyasu sim providers have price simulators on their website so you can calculate approximately how much you’ll have to pay.

    There is also a 3,000 yen first-time fee which is similar to standard network providers, but most kakuyasu sim providers allow their users to end the contract after 6 months or a year for free, some even offer promos like free services for a month. Also, if you opt for the smartphone set, you will receive the option to pay for the smartphone handset in full beforehand or you can choose to pay it in installments across 2 years.

    While kakuyasu sim providers do not offer unlimited call services, they do offer discounts such as half price on phone calls using their calling application. A standard call using the kakuyasu sim is 20 yen for 30 seconds but becomes 10 yen for 30 seconds using the kakuyasu sim providers free application.

    Application process

    There are a number of kakuyasu sim providers in Japan offering almost the same kind of service with differing costs and it’s up to you to you which you choose. Some of the well-known kakuyasu sim providers include DMM mobile, Big Globe, IIJmio, U-mobile, Mineo, and Rakuten Mobile. Currently, a few Kakuyasu Sim Providers offer unlimited calls for calls under 5 or 10 minutes (several hundred times within a month).

    There are two ways in which you can apply for a kakuyasu sim service. The first is by visiting a store (although not all providers offer them), or applying online, which is easier and more convenient. However, you will need a credit card to process the application.

    At the information input page, you just need to fill in all the details and provide valid identification by taking a clear photo and attaching it to the online application as well as your credit card details. You’ll then receive confirmation by email if your application has been processed.

    Please note that the data/voice sim or smartphone set will only be sent to the address indicated. Also, you must be home to receive it and it usually takes around 2 to 3 days from the date of the application to be delivered.

    Pros and cons of kakuyasu sim

    With most things, there are always pros and cons so here is a summary to help you decide whether a kakuyasu sim is the right decision for you:


    • Does not come with an e-mail address like the other major network providers
    • Do not offer unlimited calls to the same or other networks except for a few
    • You can only apply for a voice sim if you have a credit card. While some allow bank transfer, some only allow it for data sim in accordance with the Japanese Mobile Law


    • It’s cost effective and is generally half the price of major network providers.
    • Perfect choice for those who don’t make phone calls often, you can use your own unlocked smartphone
    • Not bound to a long-term contract, can negotiate an end-date of the contract with the kakuyasu sim provider

    Basically, kakuyasu sim is perfect for anyone looking for a cheap and easy mobile option in Japan.

    Personal experience

    With mobile expenses being a large part of my monthly bills I decided to purchase a contract with the kakuyasu sim provider, U-mobile, as soon as I arrived back to Japan. Last year, I paid roughly around 12,000 yen a month with a standard network provider which was actually more than my monthly gas, water, and electricity bills combined! Now I only pay around 3,200 yen a month for U-mobile’s smartphone set.

    Since I don’t make many phone calls, it only adds up to around 1,000 yen for a whole month’s worth of calls which is approximately 50 minutes. Although, I wish I knew Rakuten Mobile offered an unlimited 5-minute call service earlier! Each kakuyasu sim provider has a list of smartphones that are compatible with the service so you can check it out beforehand if you’re planning to buy an unlocked one first. I also tried the sim with my unlocked overseas Note 4 and it worked even though the phone wasn’t yet released in Japan and wasn’t on the list. Note that if you don’t opt for the smartphone set, your monthly costs will be cut in half or more which makes it even more affordable.

    I have been using the kakuyasu sim service for a month and the signal and data connection is the same with a standard network provider service, so I haven’t encountered any downsides with it yet. So if you’re living in Japan and want to get rid of the high monthly mobile cost, then why not consider switching to a kakuyasu sim instead?

    U-Mobile Website*Japanese Only
    Mobile Rakuten Website*Japanese Only

    Related Articles:
    Three Useful Mobile Phone Apps When Touring Japan
    Japanize your iPhone with these Uniquely Artistic Covers!