Keeping your number when you switch carriers in Japan (MNP)

How do I keep my number when I switch carriers?

Use one-stop if both carriers support it. Otherwise ask the old carrier for a reservation number (予約番号) and give it to the new carrier. One-stop (MNPワンストップ) started in May 2023 (ahamo's explainer), and works only when both carriers support it: UQ mobile says some carriers still need the number first (UQ mobile).

1. Apply in the name on the old line. The new carrier asks the old one to confirm the name (povo2.0). Rakuten Mobile requires the same name at both carriers (Rakuten Mobile).
2. With one-stop, start at the new carrier. Then confirm the cancellation reservation in the old carrier's web account. au, povo2.0 and UQ mobile give you 5 days to finish the new application after that (au's notice, povo2.0, UQ mobile).
3. Without one-stop, ask for the number. It is a 10-digit code (IIJmio's guide). Note its expiry date; the new carrier asks for it.
4. Apply to the new carrier within about 5 days. Most want at least 7 to 10 days left on the number.
5. Cancel nothing. The old line ends by itself when the new carrier finishes the move (povo2.0's notice). IIJmio will not issue a number once you have applied to cancel (IIJmio).

Is a reservation number valid for 15 days, 14 days or 8 days?

Fifteen days, counting the day you request it. docomo, au, SoftBank, Rakuten Mobile, ahamo, povo2.0, LINEMO, UQ mobile, Y!mobile, IIJmio and mineo each say so on their own pages (the table links each one; SoftBank words it as "within 15 days of issue"). We used the carriers' pages, not summaries by other sites.

You may have seen 14 or 8 elsewhere. Both come from real rules that are about something else:

• 14 days: Sakura Mobile's help center says its numbers "expire 14 days after issuance" (Sakura Mobile). Counting the day of issue as day 1, a 15-day number runs out on the 14th day after it, so the last day is the same.
• 8 days, first meaning: Sakura Mobile asks for at least 8 days left on a number you bring to it (Sakura Mobile). That is a minimum for joining, not how long a number lasts.
• 8 days, second meaning: Y!mobile says you cannot cancel a new MNP contract from the eighth day after the move is complete (Y!mobile's notice).

The minimum matters more than the 15. Several carriers will not take a number that is close to its last day. docomo, au, ahamo, UQ mobile and mineo ask for at least 10 days left. Rakuten Mobile and IIJmio ask for 7 on a web application, and Rakuten Mobile will take any valid number in one of its shops. The carriers do not say whether the day you apply counts, so leave a day of margin: apply within about 5 days of getting the number.

A number is not always instant. IIJmio takes about 1 to 4 days to issue one, and Sakura Mobile 2 to 3 days. IIJmio's 15 days start from the day it issues the number, not the day you ask. Sakura Mobile also says that a SIM ordered from it arrives 5 to 7 days after approval.

We found no minimum for LINEMO, povo2.0, Y!mobile or SoftBank. They show as Checking.

Does it cost anything to move my number?

The MNP fee is ¥0 at docomo, au, SoftBank, Rakuten Mobile, ahamo, povo2.0, LINEMO, Y!mobile, IIJmio and mineo, and UQ mobile calls it generally free. Sakura Mobile charges ¥1,100 per number, charged when it processes the request (Sakura Mobile).

A separate cancellation fee (契約解除料) can apply to a line less than a year old. LINEMO charges ¥990 or ¥1,100 (LINEMO). Y!mobile charges one on lines that start on or after 1 July 2026 (Y!mobile). au and UQ mobile charge up to ¥1,100 on lines started on or after 1 October 2025 (au, UQ mobile). ahamo charges ¥1,100 on lines opened on or after 1 July 2025 (ahamo). Rakuten Mobile charges a cancellation fee (解約事務手数料, cancellation handling fee) of up to ¥1,078 on lines started on or after 1 April 2025 (Rakuten Mobile). We did not check the cancellation terms of docomo, SoftBank, IIJmio, mineo, Sakura Mobile or Mobal. The new carrier's own contract fee is a third charge and is on each review.

SoftBank's pages disagree. Its fee page says there is no MNP-out fee. Its reservation-number page still says the move has a fee and links to a fee page. We followed the fee page (SoftBank's fee page), which answers the question directly, and the weekly check re-reads it.

What goes wrong for foreign residents?

The usual failure is a name that does not match. The other problems are ones the carriers themselves list.

• Name spelling. Sakura Mobile says the new carrier sees only what you type on the MNP form, and some refuse a number when the name differs from the ID (Sakura Mobile). Type your name as it is on your residence card.
• Japanese-only steps. IIJmio issues a reservation number only on its member page, never by phone (IIJmio). ahamo issues it in My docomo, and a shop cannot (ahamo). ahamo told a mystery shopper it has no English support, and IIJmio's support chat page says its Support Center is Japanese only.
• A request that comes too late for the month. Sakura Mobile says a request made after the 28th may not arrive in time to end the contract that month, and you then pay the last month in full.
• A data plan. On the data type of Rakuten's Saikyo plan (Rakuten最強プラン), the number you use for SMS cannot be moved out. Change to the regular type first (Rakuten Mobile).
• The ID check at the new carrier. It is a separate step from the move. Whether the carrier accepts your residence card online, including the second-generation card, is on the verification tracker.
• Canceling first. Canceling before you move the number loses it. Mobal's pages say so for its own plans: Mobal MNP.

Which providers take a number from another carrier?

Mobal takes a number from another carrier only on its Voice+Data 5G eSIM with a monthly plan (Mobal's porting article). The 5G SIM Card and Voice Lite give a new number. The Mobal MNP page has the steps and what it says about leaving.

Order the Mobal eSIM, which can take your existing number

Mobal Japan eSIMs

Sakura Mobile asks for at least 8 days left on the number, and its SIM arrives 5 to 7 days after approval, so request the number from your old carrier only when you are ready to apply (Sakura Mobile's guide). Its fee for leaving is ¥1,100. Plans, ID rules and payment are on our Sakura Mobile review.

What happens after you click: the provider's English page opens. You choose a plan, give your ID, and enter your reservation number and its expiry date during the application.

How we checked

We read each carrier's own pages on October 21, 2026: its MNP, cancellation or fee page, its FAQ, or its important-matters notice. Every day count, fee and step on this page is tied to a sentence on one of them, saved in our data file with its address and date. Where a carrier's pages did not say, the cell reads Checking. au's and UQ mobile's notices are PDFs, and Sakura Mobile's help center blocks automatic reading, so those facts are on a manual review list. We have not moved a number ourselves, so none of this is first-hand experience.

Not covered: the carriers' English pages (we read the Japanese ones), what each new carrier asks of an incoming number beyond the days left, and LIBMO, DTI SIM, BIGLOBE Mobile, OCN and NUROmobile. The Mobal facts are on the Mobal MNP page.

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