For a family, the thing that decides this is not the price. It is how much data one phone can pass to everyone else’s. On the plans sold as unlimited, that sharing stops at about a gigabyte a day.
eSIM, pocket Wi-Fi, or a SIM card?
Your own phone decides, and you can check it tonight. An eSIM is a plan you install from a code before you leave home. There is no counter to find and nothing to hand back. But it only works on a phone that is not tied to one carrier.
Sakura Mobile puts two conditions on it. The phone has to be unlocked. You also have to have finished paying it off. A phone still on a US carrier installment plan will be refused. Ubigi asks for the same thing: an unlocked, eSIM-capable device.
- If your phone is unlocked — an eSIM is the least work. Nothing to collect at the airport, nothing to mail back.
- If it is locked to your carrier, or you would rather not set up four phones — rent a pocket Wi-Fi. It is a small box that makes its own network, so it does not care what your phones are tied to. Sakura Mobile gives this as its own answer for locked devices.
- If your phone takes a plastic card but not an eSIM — buy a physical SIM. These are sold at airport counters and from vending machines. At the end of the trip you throw the card away instead of returning it.
Should one phone share with everyone, or should each parent have a line?
If you plan to share from one phone, budget about a gigabyte a day. Both Japanese operators publish this, and neither hides it — but it is easy to miss under the word unlimited.
IIJ sells an unlimited prepaid SIM, then caps the sharing. The 10-day plan allows 9 GB, the 15-day plan 14 GB, and the 31-day plan 30 GB. Once you pass the cap, the speed drops to 128 kbps for the rest of the trip. Sakura Mobile’s unlimited eSIM works the same way, and the cap tracks the length of the stay. It is 3 GB over 4 days, 9 GB over 10 days, 15 GB over 15 days, and 30 GB over 31 days.
Divide that by the people leaning on it. Nine gigabytes across ten days is 900 MB a day for the whole family. The phone holding the plan can keep using data after the cap; the phones borrowing from it are the ones that slow down.
Two ways out, both ordinary:
- Give each parent a line. Two unlimited eSIMs means two full-speed phones and no sharing at all. Sakura Mobile takes 10% off when you buy two or more at once.
- Rent a pocket Wi-Fi instead. Sakura Mobile’s rental is unlimited with no cut-off, takes up to 15 devices at once, and holds a 20-hour battery. It starts at ¥299 a day (¥329 with tax). One box covers both parents, both tablets, and a laptop.
What do the plans actually cost?
Between roughly ¥1,500 and ¥6,000 for a normal family trip, depending on how you buy. Read these as the shape of the market, not as quotes — two of the three change with your dates.
- Ubigi — a Transatel/NTT brand that runs on the KDDI and NTT Docomo networks. It prints fixed prices. Ten gigabytes over 30 days costs US$16.50. Unlimited for 15 days costs US$39, which runs at full speed to 30 GB and then at 2 Mbps. The plan turns itself on when you land, and sharing to other devices is allowed.
- Sakura Mobile — Japanese, English-speaking support, and plans for stays up to 90 days. It starts at ¥1,500 (¥1,650 with tax), but the price page will not show you a number until you enter your start and end dates. Payment is taken in yen only.
- IIJ Japan Travel SIM — the official spec page prints no price at all; it says the retailer sets it. The version worth knowing about is the eSIM sold from the copier machines in FamilyMart stores. There IIJ does publish figures: ¥2,480 for 3 GB up to ¥5,780 for 55 GB, before tax, on 30-day plans. It has been on sale that way since November 25, 2025, at about 16,400 stores.
That last one is the answer to a late arrival. If you land at eleven at night with a sleeping toddler and every counter is shut, a convenience store copier is still on. You pick the plan on the machine, pay at the register, and get a code to register online.
Where can you pick one up at the airport?
Counters cluster in the arrivals halls, and most of them close between 21:00 and 23:00.
| Airport | Where | Hours | Official page |
|---|---|---|---|
| Haneda (HND) | Terminal 3, arrivals hall on 2F and departures on 3F; Terminal 2, international arrivals on 2F; Terminal 1, vending machines on B1F and 2F | T3 counters 6:00–23:00; T2 arrivals 5:45–23:00; T1 machines 5:00–24:00 while the building is open | Haneda |
| Narita (NRT) | Terminal 1 arrivals on 1F (north and south wings), Terminal 2 arrivals on 1F, Terminal 3 on 1F. SIM vending machines also stand on 2F of Terminal 2, before customs | JAL ABC counters 6:30 until one hour after the last international arrival; other counters 7:00–21:00 | Narita |
| Kansai (KIX) | Terminal 1, arrivals on 1F, with more counters upstairs on 4F; Terminal 2 on 1F | Counters 6:00–23:00; the SIM vending machines and pickup lockers run 24 hours | Kansai |
| New Chitose (CTS) | International terminal, 2F; domestic terminal, 1F | International counters 9:00–19:00, one of them closing at 17:00; the GLOBAL Wi-Fi locker 7:00–18:30. Domestic counter 9:00–18:00, shut 13:00–14:00 | New Chitose |
| Fukuoka (FUK) | International terminal, 1F, all of it before security | Counters 7:00–21:30; the SIM vending machine 5:00–22:40 | Fukuoka |
| Naha (OKA) | International arrivals hall, 1F; a second machine in the domestic arrivals hall, 1F | International 7:30–21:00; domestic 6:00–24:00 while the building is open | Naha |
Three things the table does not say out loud:
- Narita states that these counters exist only before departure passport control. On the way in, you walk past them. On the way out, once you are through passport control, there is no counter left.
- Kansai is the one that stays open all night, because its SIM machines and pickup lockers are unstaffed. New Chitose is the tightest — its international counters are gone by 19:00.
- Naha’s official page lists Wi-Fi rental only. No SIM counter appears on it, so do not plan on buying a card there.
What about the kids’ phones and tablets?
A travel eSIM carries data and nothing else. There is no Japanese phone number attached, so a child’s phone running one cannot be reached by an ordinary call. Ubigi says the same about its plans and points people to messaging apps for calls and texts.
For a family that means two practical things. Set up the calling app you will actually use before you fly, because that is the only way anyone reaches that phone. And if the children carry tablets rather than phones, a rented pocket Wi-Fi is less work than four separate plans. It takes 15 devices, and each one joins a network the way it does at home.
What to do before you fly, and on the way home
Install the eSIM at home, while you still have Wi-Fi. Installing one needs an internet connection. IIJ’s own instructions start by telling you to connect to Wi-Fi, which is awkward to arrange in an arrivals hall. Sakura Mobile confirms you can install from your departure country.
Then check which day the clock starts, because the two plans differ. On Sakura Mobile’s unlimited 5G eSIM, the period begins when you arrive in Japan — install it early and you lose nothing. On its 3 GB-per-day eSIM, the day you install it counts as day one, so installing a week early costs you a week. Ubigi’s plans start by themselves when you land.
Download Japanese into your translation app before you fly, and know what an offline map will not do. Google states that transit, walking, and cycling directions are all unavailable offline, even inside an area you downloaded. Those are how a family moves here. An offline map tells you where you are; it will not find you the next train. Translation is the download that pays off. Connect to Wi-Fi and download Japanese. After that the camera will read a sign or a menu with no connection at all.
Going home:
- A SIM card is yours. Throw it away. There is nothing to return.
- A rented pocket Wi-Fi goes back in the prepaid envelope, into any Japan Post mailbox, by midnight on the return date. No stamp needed.
- Do that before you go through security. Sakura Mobile states there are no mailboxes or post offices past the security and passport checkpoints. Mail it while you are still in the check-in hall, before you are managing bags and children in a line.
On the numbers here
Every figure above was read from the operator’s or the airport’s own site on August 18, 2026. Two of them move. Sakura Mobile prices by your exact travel dates, and IIJ leaves the price of its card SIM to whichever shop sells it. Airport counter hours are the ones each airport publishes, and airports revise them. If you are reading this much later, open the source links before you budget or plan an arrival around a counter.