What to Check in a Mobile Phone Contract in Japan Before You Sign
Updated: 2026-09-05
Quick answer
Hi, I'm Miya, and I help newcomers settle into life in Japan. A mobile contract here isn't scary, but it does have a few boxes worth reading slowly before you sign. The ones that matter most are simple: how long you're tied in and how to cancel, what the plan actually gives you for data and calls, whether you're getting an eSIM or a physical SIM, and what ID you'll need for the identity check.
You don't need to compare every carrier or memorise fine print. You just need to know what each part means, so that when the form asks a question you understand what you're agreeing to. Let's go through it together, calmly, one section at a time.
Contract period and how to cancel
The first thing I always check is whether there's a minimum contract period and what happens if you leave early. Many newer plans have no lock-in and no cancellation fee, but not all do — some still tie you in for a set number of months or charge a fee if you cancel before then. Read this before anything else, because it's the part that's hard to undo later.
Also look at how cancellation actually works: whether you can do it online or need to visit a store, and how much notice is required. If you think you might switch phones, move, or leave Japan, this section tells you how easily you can walk away. When the exact terms aren't clear on the sign-up screen, check the carrier's official page rather than guessing.
What the plan includes: data and domestic calls
Next, read what you're paying for each month. For data, check the monthly allowance and what happens when you use it up — some plans slow your speed for the rest of the month, others let you buy more. Think about how you actually use your phone: maps, messaging, and video all pull different amounts, so pick an allowance that fits your real life rather than the biggest number.
Then check how domestic calls are handled. Some plans charge per minute, some include a set number of free minutes, and some offer an unlimited-calling option for an extra monthly fee. If you rarely make voice calls and mostly use messaging apps, a small or pay-as-you-go call setup may be plenty. The official plan page will spell out the current details, so use it to confirm before you commit.
eSIM or physical SIM: which you're getting
Your line comes as either an eSIM or a physical SIM card, and it's worth knowing which one you're choosing. An eSIM is a digital profile you download straight to a supported phone — nothing arrives in the post, so you can often be connected the same day. A physical SIM is the small card you slot into your phone, which needs to be shipped to you or picked up, and works in almost any device.
Before you pick eSIM, confirm your phone actually supports it — most recent models do, but not all. It's also good to know whether you can switch types later or move the line to a new phone, in case you upgrade. If you're unsure whether your device is eSIM-compatible, the carrier's official page usually lists supported phones.
ID and your residence card in the eKYC step
Signing up online includes an identity check, often called eKYC. This is the step where you prove who you are, usually by photographing an ID document and taking a short selfie or a quick video so the photo can be matched to your face. It sounds formal, but it only takes a few minutes on your phone.
For most newcomers, the ID you'll use is your residence card (zairyu card), so have it ready and make sure the details on it are current. Take the photos in good light, keep the card flat and fully in frame, and check that the name and address you type match your documents exactly — mismatches are the most common reason an application gets held up. Once the check passes, you're through the hardest part.
Ready to sign? Getting connected same-day
Once you know these four things, signing up stops feeling like a leap of faith. And getting a Japanese number is exactly the step this campaign is here to help you through — the sooner you have a line and data, the sooner everything else in Japan gets easier.
In practice it's gentle: with your residence card in hand, you apply online, pass the eKYC check we just talked about, and if your phone supports eSIM you can be connected the same day — often in around fifteen minutes, without visiting a store. Check the official page for the current terms before you apply, and I'll be here to help with the mobile part so you can get on with settling in.
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