Number Portability (MNP) Procedure

The MNP Japan procedure lets you change mobile carriers while keeping the same phone number.¹ You request a transfer code or use the one-stop path, sign with the new carrier, and the old contract ends automatically at switchover.²¹

Confirm current details with official sources

Procedures, fees, and requirements can change. Confirm current details at the Ministry of Internal Affairs and Communications mobile phone portal site and each carrier's MNP page.

Overview

MNP (em-enu-pī, "Mobile Number Portability") is the national system that keeps your number when you change carriers.¹ Japan introduced it in 2006, then reformed it in April 2021 to make transfer-out effectively free and online applications 24-hour.¹

The same rule applies nationwide under MIC guidelines. Carrier channels differ (web, phone, shop), but the portability right itself does not vary by ward or nationality.¹³

Who this guide is for

This guide is for residents with an active Japanese mobile contract who want to switch carriers and keep the number.²¹ It covers both the reservation-number path and the one-stop path, plus fees, timing, and offer pitfalls.

New arrivals without a Japanese number to port need a new contract instead. That onboarding path, including prepaid bridge options and ID hurdles, sits outside this guide.

How MNP Works in Japan

Japan offers two MNP routes to the same outcome. The conventional route uses a reservation number from the current carrier. The one-stop route skips that step and completes everything through the new carrier's website.²¹

One-stop works only when both the old and new carriers support it for web applications. DOCOMO has offered it for online applications since May 24, 2023.² MIC revised the MNP implementation guidelines that same day, following its April 1 to May 8, 2023 opinion solicitation and the May 2021 taskforce recommendation to add one-stop within about two years.³

Reservation-number path and one-stop path

In the conventional path, you obtain an MNP予約番号 (MNP yoyaku bangō, "MNP reservation number") from the current carrier, then present it to the new carrier.¹ In the MNPワンストップ (MNP wan-sutoppu, "MNP one-stop") path, you apply only on the new carrier's website and authenticate into the old carrier's page mid-flow.¹³

The eligible-carrier list is broad and growing: DOCOMO, ahamo, au, UQ mobile, povo, SoftBank, Y!mobile, LINEMO, Rakuten Mobile, mineo, IIJmio, NURO Mobile, BIGLOBE Mobile, AEON Mobile, and others (as of 2026-04; confirm current eligibility with the MIC portal site).⁴ Storefront applications and any pair outside that set still use the reservation-number path.²⁴

The chart above shows the two routes converging at switchover.²¹ Pick the route your carrier pair supports rather than assuming one-stop is universal.

What moves and what does not

Only the phone number ports. A carrier-issued email address does not carry over, and data migration stays your task.¹⁴

Points saved with the old carrier can expire, so gov-online advises spending them before switching.¹ An unpaid device-installment balance survives the switch.¹ Family-discount structures can also shift for members staying behind, raising their charges.¹

One narrow exception exists for mail: Rakuten Mobile documents a paid carrier-email portability option at 330 yen per month (as of 2026-09).⁵ Treat it as an add-on service, not part of MNP itself.

Getting an MNP Reservation Number

Skip this section if both carriers support one-stop and you apply online. Otherwise the reservation number is the ticket that makes the switch possible.²⁴

Where to request it

Request the number from the current carrier by web, phone, or shop counter.¹ Most carriers accept web requests and generally notify the number by SMS the same day.¹

DOCOMO examples include phone 151 from DOCOMO handsets or 0120-800-000 from landlines, 9:00 to 20:00, plus the My docomo web flow (as of 2024-06; confirm current contacts with DOCOMO).² J:COM documents per-carrier web paths such as My docomo, My au, My SoftBank, my Rakuten Mobile, ahamo, my UQ mobile, povo, My Y!mobile, and LINEMO My Menu, with phone fallbacks including au 0077-75470 and SoftBank *5533 or 0800-100-5533 (as of 2024-09).⁴ Online MNP applications run 24 hours under the post-reform rule.¹

Use the web channel to avoid retention pitches

Unrequested retention offers and stay-incentive points during MNP issuance are prohibited under the revised guidelines.¹ The web channel also creates a written record of the number and its expiry.

Validity window and remaining-days rule

The reservation number is generally valid 15 days including the issue day, and an expired number needs reissue (as of 2026-09 government and carrier pages; confirm current validity with your carrier).²⁶¹⁴ Some carriers note the window can differ by company.¹

One foreign-resident provider states 14 days validity in its own FAQ (as of 2026-06).⁷ Read the general rule as 15 days typical with carrier variance, and always go by the expiry printed on your number.

Receivers also impose a remaining-days minimum, so gov-online advises applying immediately after issuance.¹ DOCOMO Online Shop applications require at least 10 days remaining (as of 2024-06).²

J:COM requires at least 10 days remaining at application.⁴ Sakura Mobile requires at least 8 days remaining at sign-up (as of 2026-06).⁷

Switching Procedure Step by Step

The flow is short: prepare documents, apply to the new carrier, then activate the new SIM or eSIM. The old contract ends automatically when switchover completes.²¹

The steps below assume the reservation-number path. For one-stop, drop the first step and start at the new carrier's site.²¹

Each box maps to the prose in this section.²¹⁴ Activation is the moment service moves, so time it when you can spare a short offline window.

What to prepare

Bring the reservation number (except one-stop online), a subscriber ID document, and payment credentials.²¹ DOCOMO accepts a Japanese driver's license or My Number Card showing the current address with no photocopy, and shop payment setup uses a credit card or bank card plus bankbook and seal under the subscriber name.² Gov-online lists the shop set as reservation number, ID such as license or passport, and credit or cash card.¹

The sender-side and receiver-side contract-holder names must generally match.²⁴ Transfers from another person's contract are not accepted, so confirm the name on the current contract before applying.

Item	Amount	As of	Notes
MNP issuance, web request	0 yen	2021-04	Reform rate1
MNP issuance, shop or phone request, regulatory cap	Up to 1,000 yen plus tax	2021-04	Majors charge 0 yen in practice1
Receiver handling fee, DOCOMO shop example	4,950 yen incl. tax, billed next month	2024-06	Waived at docomo Online Shop2

The table reflects the stated rates at the given dates; confirm current figures with each carrier before budgeting. Issuance being free does not remove the receiver-side handling charge or any surviving device balance.

From application to line switchover

Apply at the new carrier shop or website with the reservation number.²¹ Online applicants enter the number and upload ID, and the SIM ships promptly when the application has no defect.¹

Shop applications generally run 9:00 to 20:00 because of inter-carrier system linkage.² J:COM states weekend and holiday switchover is possible within 9:00 to 20:00 reception, with 20:00 to 21:00 procedures sometimes rolling to the next day.⁴

Do not cancel the old contract yourself first

The old contract ends automatically when the new-carrier contract and switchover complete.²¹⁴ Canceling early strands the number instead of porting it.

Activation creates a short offline gap. J:COM describes minutes to tens of minutes during SIM-change activation.⁴ Plan calls and two-factor SMS around that window rather than during it.

Costs and Timing

MNP issuance is effectively free, but the full switch still has moving parts. Receiver fees, device balances, and SIM delivery set the real budget and schedule.²¹

MNP and contract fees

Transfer-out issuance costs 0 yen for web requests from April 2021 reform, while shop and phone requests are capped at 1,000 yen plus tax with major carriers actually charging 0 yen even there (as of 2021-04; confirm current figures with your carrier).¹ Before the reform, transfers typically cost around 3,000 yen.¹

The system dates to 2006.¹ Excessive retention behavior, including unrequested plan pitches or stay-incentive points to stop MNP, is prohibited under the revised guidelines.¹

A receiver-side handling fee can still apply separately. DOCOMO charges 4,950 yen including tax at shops and waives it online (as of 2024-06).² Older fixed-term contracts can also carry a separate early-termination charge distinct from MNP issuance, so confirm the current contract terms rather than assuming zero.¹

How long the switch takes

Same-day carrier change is possible at a shop, while online orders wait for SIM delivery of about 1 to 3 days.¹ The interruption at switchover itself is short, on the order of minutes and under one hour per the J:COM FAQ wording of minutes to tens of minutes.⁴

Treat eSIM as the faster variant when both handset and carrier support it. Physical SIM timing depends on shipping, not on the MNP rule itself.¹⁵

Good to know

Strategic MNP cashback offers deserve a full cost read

New-customer MNP offers are commonly point rewards with entry, plan, and app-use conditions rather than unconditional cash (as of 2026-09; confirm current offers with each carrier).⁵ Rakuten Mobile offers 10,000 points for MNP against 7,000 for other new sign-ups, paid as time-limited points in installments after entry, plan start, and a Rakuten Link call over 10 seconds (as of 2026-09).⁵

A September 2026 comparison puts SIM-only MNP rewards around 10,000 to 20,000 yen-equivalent at major carriers, with device-set combinations reaching about 36,000 yen in value at Rakuten (as of 2026-09).⁸ That compilation draws on official campaign pages rather than a single primary source, and every figure expires with its campaign.⁸

Store-level cashback at mass retailers and multi-carrier shops varies further by month, line count, and bundled options. Read any 10,000 to 40,000 yen per MNP-in figure as campaign-dependent rather than guaranteed, and check whether the reward is cash, points, or a device discount before counting it as savings.⁸

Carrier email and points do not follow your number

Carrier email stops and saved points can lapse at switchover.¹⁴ Move important accounts to a free mail service before applying, and spend or transfer points while the old contract is still active.¹

The same logic covers bundled discounts tied to the old carrier. Confirm what the remaining family lines will pay after your line leaves, since their discount base can shrink.¹

Name mismatch stops the application

The application fails when sender and receiver names differ, including family-member or friend contracts.²⁴ DOCOMO and J:COM both require the same contract-holder name on both sides.²⁴

When the user and the subscriber differ, prepare the extra identity documents the receiver lists. Do not submit under a different name hoping the carriers will reconcile it.

Old contracts can still carry a termination fee

Check the current contract period before timing the switch. Issuance being free does not erase a separate termination charge that a pre-reform fixed-term contract may impose.¹

Gov-online treats installment balances and family-discount effects as separate surviving items alongside the freed issuance fee.¹ No universal current termination figure is stated here because none was sourced to a single primary schedule; read your own contract instead.

See also

• Prepaid SIMs for the First Month
• Internet and TV: Utility Setup Overview
• Bank Account in Japan for Foreigners: The Six-Month Rule
• Big Three Carriers vs. MVNO Sub-Brands
• eSIM and Multi-SIM Setups in Japan
• Mobile Plan Considerations for Foreign Residents

References

Footnotes

1. Cabinet Office Government Public Relations Online (gov-online.go.jp). "番号を変えずに携帯会社を乗換え! MNPの転出手数料が原則無料に!" https://www.gov-online.go.jp/article/202107/entry-10146.html ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³ ↩²⁴ ↩²⁵ ↩²⁶ ↩²⁷ ↩²⁸ ↩²⁹ ↩³⁰ ↩³¹ ↩³² ↩³³ ↩³⁴ ↩³⁵ ↩³⁶ ↩³⁷ ↩³⁸ ↩³⁹ ↩⁴⁰ ↩⁴¹ ↩⁴² ↩⁴³ ↩⁴⁴

2. NTT DOCOMO. "Procedures for Switching from Another Carrier to DOCOMO with Mobile Number Portability (MNP)." https://www.docomo.ne.jp/english/support/procedure/mnp_subscribe ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶ ↩¹⁷ ↩¹⁸ ↩¹⁹ ↩²⁰ ↩²¹ ↩²² ↩²³ ↩²⁴

3. Ministry of Internal Affairs and Communications (MIC). "Results of Solicitation of Opinions on Draft Guidelines for Implementing Mobile Number Portability for Mobile Phones and PHS, and Announcement of the Revised Guidelines." 2023-05-24. https://www.soumu.go.jp/main_sosiki/joho_tsusin/eng/pressrelease/2023/5/24_1.html ↩ ↩² ↩³

4. J:COM Co., Ltd. "About MNP." https://www.jcom.co.jp/en/service/mobile/usage/mnp.html ↩ ↩² ↩³ ↩⁴ ↩⁵ ↩⁶ ↩⁷ ↩⁸ ↩⁹ ↩¹⁰ ↩¹¹ ↩¹² ↩¹³ ↩¹⁴ ↩¹⁵ ↩¹⁶

5. Rakuten Mobile. "Join Rakuten Mobile and Get Rewarded! Switch from another carrier (MNP) and get 10,000 points." https://network.mobile.rakuten.co.jp/en/campaign/mnp/ ↩ ↩² ↩³ ↩⁴

6. SoftBank Corp. "Switchover/MNP (Mobile Number Portability)." https://www.softbank.jp/en/mobile/shop/buy/mnp/ ↩

7. Sakura Mobile. "What is MNP?" Updated 2026-06-18. https://support.sakuramobile.jp/hc/en-us/articles/360020534351-What-is-MNP ↩ ↩²

8. LiPro (IID, Inc.). "MNPキャッシュバック・ポイント還元を比較." Updated 2026-09-01. https://internet.iid.co.jp/mnp-cashback/ ↩ ↩² ↩³