If you want to hold on to a Japanese phone number as cheaply as possible, the low-cost voice SIMs priced around ¥290 a month are an obvious place to start. Two of the best-known options are Japan Communications’ “Rational Simple 290” and HIS Mobile’s “Jiyu Jizai 290.” Both are well suited to simply keeping a number alive, but they differ in how data costs grow, how calls are priced, and how they feel in day-to-day use. This article compares the two calmly, from the point of view of people who spend long stretches away from Japan—those living abroad, on extended stays, or traveling back and forth. The assumption throughout is that you want to keep the fixed cost of holding a number low, while arranging your overseas data separately.
- For keeping a number only, using under 1GB a month, Japan Communications tends to be cheaper
- If you sometimes use a few GB, HIS Mobile is worth comparing too
- Both plans support voice, SMS, and eSIM, making them suitable for keeping a number
- Whether you can receive SMS while abroad must be confirmed on each carrier’s official site before signing up
- Overseas data is easier to manage if you cover it separately with a data-only eSIM
- If you want to keep only a number and use under 1GB a month, Japan Communications’ “Rational Simple 290” is an affordable choice. If you occasionally use a few GB, HIS Mobile’s “Jiyu Jizai 290” is also worth comparing.
- Both support voice, SMS, and eSIM and suit number retention. However, data allowances are small, so it keeps things simpler to plan on covering your connectivity while traveling or staying abroad with a separate data-only eSIM.
- Whether you can receive SMS abroad should be checked on each carrier’s official site. For people living abroad, it matters to choose not just on the lowest monthly price but on whether you can still receive verification SMS when it counts.
The information in this article is organized from each carrier’s official sources as of June 2026. Pricing, data allowances, call rates, and the conditions for receiving SMS abroad may change, so please check the latest details on each carrier’s official site before signing up.
What does “keeping a number” actually mean? Where people living abroad get tripped up
“Keeping a number” refers to a way of using a plan whose main purpose is to preserve the Japanese phone number itself, rather than to use it heavily for calls and data. When you live abroad for a long time, a Japanese number becomes more than just a contact detail. Banks, brokerages, government procedures, and logins for various apps may all require SMS verification sent to a Japanese number for identity confirmation. If you cancel the number, you may no longer be able to complete these verifications, and resetting them can be a hassle. That is why the need to “keep it even though I rarely use it” arises, and why the cheapest possible voice SIMs get chosen.
One thing to watch, however, is that an SMS sent to your Japanese number cannot always be received as-is while you are abroad. Whether reception works depends on the plan and how the line is handled, and it can change. Choosing purely “because it’s cheap” can lead to a situation where the very verification SMS you need never arrives. When thinking about keeping a number, it’s reassuring to confirm the “conditions for receiving SMS abroad” on the official site just as carefully as the price.
Key terms
- Number-retention plan: A smartphone plan designed to keep a phone number at low cost, mainly for SMS verification and holding onto a calling number. The data allowance is often set on the small side.
- Data-only eSIM: An eSIM used purely for internet connectivity—not for a phone number or SMS. Useful when you want to arrange just as much overseas data as you need.
- Usage-based (metered) pricing: A structure where the cost rises with the amount of data used. Small amounts stay cheap, but heavy use can end up costing more than expected.
How the two plans work (pricing and how data grows)
Japan Communications’ “Rational Simple 290” offers 1GB for ¥290, with usage above that added at ¥220 per GB on a metered basis (with a cap). An optional 70 minutes of included calls (¥700) is also available, which can suit people who want to bundle short calls together.
HIS Mobile’s “Jiyu Jizai 290” starts at ¥290 for up to 100MB, with the price rising in steps according to how much you use. Calls are ¥9 per 30 seconds. It’s a design that adapts well to a range of usage, from very light to a few GB. For light use around 1GB, Japan Communications tends to be cheaper; if you sometimes reach the 5–7GB range, HIS Mobile can come out ahead in some cases. Both support eSIM, so a shared advantage is that you can sign up and set up online without waiting for a physical SIM to be mailed—even from abroad.
| Item | Japan Communications Rational Simple 290 | HIS Mobile Jiyu Jizai 290 |
|---|---|---|
| Approx. monthly price | From ¥290 (1GB) | From ¥290 (up to 100MB) |
| How data grows | 1GB + ¥220/GB (with a cap) | Metered, rising in steps |
| Voice / SMS | Yes (70-min included-call option ¥700) | Yes (calls ¥9/30 sec) |
| eSIM | Supported | Supported |
| SMS reception abroad | Check official site | Check official site |
| Best-fit data amount | Affordable up to 1GB | Can be favorable in the 5–7GB range |
* Prices and conditions are approximate as of June 2026. Please confirm call rates, SMS sending fees, additional data charges, and overseas handling on each carrier’s official site.
A closer look at “how data grows”
If your goal is to keep a number, your everyday data use is probably very small. Japan Communications uses 1GB as its baseline, and its appeal is the clarity of only adding charges for what you go over. HIS Mobile rises in steps from 100MB, so in months when you barely use anything, your cost may be lower still. That said, with usage-based pricing, background data such as app auto-updates can quietly consume data and push the bill higher than expected. For number retention, your fixed cost becomes easier to predict if you set things up to limit consumption—for example, keeping the SIM’s mobile data off by default and restricting auto-updates to Wi-Fi.
Which one suits you? (by type)
| If you’re someone who… | Suggested fit |
|---|---|
| Just wants to keep a number as cheaply as possible (under 1GB/month) | Japan Communications Rational Simple 290 |
| Sometimes uses a few GB | Compare HIS Mobile Jiyu Jizai 290 too |
| Wants to bundle short calls together | Consider Japan Communications’ 70-min included-call option |
| Wants to minimize cost month by month with fine-grained metering | Consider HIS Mobile’s stepped pricing |
The ¥290-class plans suit people who want to keep the baseline cost of number retention low, but if you live abroad you’ll want to confirm SMS reception while overseas on the official site. Even when the monthly price is similar, peace of mind in a pinch comes down to whether you can stay in a state where verification SMS can reach you. Since data is limited, deciding from the start to “add data via eSIM” lets you manage fixed cost and connectivity separately, keeping things simple.
Who this approach suits—and who it doesn’t
Suits you if…
- You want to keep a Japanese number at low cost
- You want to keep a number for SMS verification
- You’re fine handling overseas data by other means
- You want to complete sign-up and management online with eSIM
May not suit you if…
- You want to use a lot of data every month on a single SIM
- You need guaranteed, stable SMS reception abroad (reception is not guaranteed)
- You want number, calls, and data all managed with one provider
What people living abroad should check in particular
1. Conditions for receiving SMS abroad
Whether an SMS to your Japanese number can be received overseas is even more important than price. Even when reception is possible, there may be conditions, and these can change—so check each carrier’s official site before signing up. To prepare for cases where verification can’t go through, it’s reassuring to also set up identity-verification methods other than SMS, such as an authenticator app (TOTP) or email verification.
2. Whether eSIM is supported
Receiving a physical SIM from abroad is a hassle. Both plans support eSIM, so on a compatible device you can comfortably sign up and set up online. If you’re unsure whether your device supports eSIM, it’s a good idea to start by checking eSIM-compatible devices.
3. Payment method and renewals
While living abroad, payments can stop because of a credit card’s billing address or an expiry date. Since number retention is something where “if it stops, you could lose the number,” it’s worth periodically reviewing whether your payment method is kept valid.
Using number retention and a data eSIM together
While the ¥290-class plans suit number retention, their data is limited. If you split off your data while staying abroad into a data-only eSIM that lets you add only as much as you need, you can separate fixed cost (number retention) from variable cost (data while traveling), which makes management easier. Bloomy’s data plans let you choose from capacities such as 1GB, 3GB, 5GB, 10GB, and 20GB (please check coverage areas). Because pricing varies by destination and capacity, please confirm the latest prices and supported countries on the comparison page.
[bloomy_price_table]
Note that Bloomy is a data-only eSIM. It does not provide a phone number, SMS, or voice calls. Think of it as a division of roles: keep your number on a plan such as Japan Communications or HIS Mobile, and cover your data connectivity abroad with Bloomy. Calls and messages through apps such as WhatsApp may be usable in places where a data connection is available. Connection quality varies depending on the local network, your device, and the area, and usage is subject to a fair-use policy.
Common mistakes (avoidable if you check in advance)
- Choosing on monthly price alone, without checking SMS reception conditions abroad: always confirm on the official site whether you can stay able to receive verification SMS.
- Leaving additional data on metered pricing and paying more than expected: splitting data off to an eSIM makes the cost easier to read.
- Being unable to receive a physical SIM from abroad: signing up with eSIM makes management easier.
- Not preparing verification methods other than SMS: also using an authenticator app or email verification keeps you out of trouble when it counts.
What to do next
- Decide roughly how much data you use per month (under 1GB, or a few GB)
- Check each plan’s overseas SMS reception, additional data charges, and eSIM support on the official site
- Prepare with roles split: a ¥290-class plan for the number, an eSIM for overseas data
- Also set up backup methods for SMS verification (authenticator app, email)
Summary
Japan Communications’ “Rational Simple 290” and HIS Mobile’s “Jiyu Jizai 290” are both options for keeping a Japanese number at low cost. For up to 1GB a month, Japan Communications; if you sometimes use a few GB, compare HIS Mobile too. Since data is small, thinking of it separately from the start—“add overseas data via eSIM”—makes it easier to keep a verification number while holding fixed costs down. Pricing and the conditions for receiving SMS abroad can change, so don’t forget to confirm on each carrier’s official site before signing up. If you have your overseas data sorted out too, you can start using everything calmly when you travel.
Frequently asked questions (FAQ)
Common questions about keeping a number are also organized in the phone number & SMS article list. For choosing an overseas data eSIM, you can search by destination, capacity, and duration from the eSIM comparison page.
Related pages
- Articles on phone number & SMS verification
- eSIM guide (basics & how to use)
- Compare eSIM plans for your destination
- Check eSIM-compatible devices
- Frequently asked questions (FAQ)
This article is intended as general information. Each plan’s pricing, call rates, additional data charges, and whether SMS can be received abroad change over time. Please check each carrier’s official site before actually signing up. We make no guarantee that you will be able to receive Japanese SMS abroad. Bloomy is a data-only eSIM and does not provide a phone number, SMS, or voice calls.
