SIM-Only vs. Contract Phone Plans: Definitions

SIM-only phone plan (SIMのみプラン) – a mobile plan that provides service without a device. You sign up for a data plan/call plan and insert the SIM card into your own unlocked mobile phone. SIM-only phone plans are often sold online or at electronics stores, and many (especially mobile virtual network operators) have no minimum contract period or cancellation fee. In Japan this typically means bringing your own device (SIMフリースマホ) and paying only for the monthly service.

Contract (device) phone plan (契約プラン) – a traditional carrier plan where you may purchase (or rent) a mobile phone on contract while subscribing to service. Historically these had 2-year (or longer) lock-in periods and device subsidies. Today major carriers (docomo/au/SoftBank) and sub-brands (Y!mobile, UQ Mobile, LINEMO, ahamo, etc.) offer simplified contracts, but they still involve signing up for service (often with a device) through the carrier, and may include financing the mobile phone's cost.

Who Should Choose Which Phone Plan

Tourists/Short-term Visitors – Generally use prepaid SIM cards or short-term SIM-only phone plans. Prepaid/data-only SIM cards (sold at airports, electronics shops, or online) require no contract or paperwork and allow immediate use, making them ideal for stays under 90 days. If staying >3 months, a SIM-only mobile plan with no minimum term (e.g. Mobal) is usually cheaper than repeatedly buying expensive prepaid packages. Avoid multi-year contracts as early cancellation incurs huge fees.

Students/Long-Term Residents – Often opt for SIM-only mobile virtual network operator phone plans or carrier sub-brand plans. If you need a new mobile phone, a contract plan with device installments is available, but note this ties you in and requires credit checks. Many foreigners prefer SIM-only mobile virtual network operators (Rakuten Mobile, IIJmio, IIJmio's Japan Travel SIM, Sakura Mobile, etc.) because they offer month-to-month flexibility and lower rates. Carriers like Rakuten Mobile, LINEMO, or ahamo also allow SIM-only sign-up (bring-your-own-phone) with no cancellation fee.

Which is Better? For data-heavy users, Rakuten Mobile or ahamo (30GB+) may be best value. For voice-centric or low-data use, cheap SIM-only mobile virtual network operators (LINEMO 3GB plan, etc.) can be enough. Foreigners especially value SIM-only phone plans with English/visa-friendly support (e.g. Mobal). Tourists should focus on prepaid/eSIM deals.

Comparison Table: SIM-Only vs Contract Phone Plans

Feature	SIM-Only Phone Plans (MVNO/prepaid)	Contract Phone Plans (Carrier/Sub-brand)
Typical Pricing	Generally lower monthly fees (no device subsidy) – many mobile virtual network operators offer very cheap 1–5GB plans (~¥1,000+) and some unlimited data plans (Rakuten Mobile ¥3,278 for unlimited data). Prepaid SIM cards have higher per-GB cost.	Monthly fees may be higher (often ¥2,000–¥5,000+), since carriers bundle mobile network and sometimes device financing. Unlimited data plans (Rakuten Mobile, ahamo, LINEMO) are competitive but still ~¥3,000+. Contract discounts often require device purchase.
Data/Call Limits	Flexible. Choose data-only or voice+data. Many mobile virtual network operators let you pick low data usage (1–5GB) to save money. Some offer unlimited data (Rakuten Mobile) or large buckets. Typically pay-as-you-go or tiered data. SMS/voice add-ons available.	Carriers offer tiered plans (e.g. 30GB or unlimited data) that include voice minutes or bundled benefits. Often include free domestic calls (via apps like Rakuten Link or options) or large data allotments.
Contract Length	Usually none or month-to-month. Many mobile virtual network operators and sub-brands do not impose a 2-year lock; you can cancel anytime with no penalty. Even prepaid has no obligation.	Often had 2-year terms, though major carriers have phased out mandatory terms as of 2021. However, older device installment plans may still require multi-month commitments. Cancellation fees on device installments may apply if paid off early.
Language Support	Limited (Japanese) for most mobile virtual network operators – many Japanese sites and support only. Exceptions: Mobal, Sakura Mobile, YOLO etc. cater to foreigners with English/Chinese support. IIJmio's Japan travel SIM even has English/Chinese FAQ.	Major carriers and sub-brands have some English materials: Rakuten Mobile and LINEMO offer English websites and basic support; SoftBank/LINEMO brands have some English pages. In big-city stores of SoftBank, au, Y!mobile you can find English-speaking staff. Overall, easier to find English help on carrier sites than on small mobile virtual network operators.
Cancellation/Fees	No cancellation fee for month-to-month mobile virtual network operator phone plans (no lock). Prepaid SIM cards require no termination. Simply stop using service.	Carriers may charge early termination fees if canceling before a promotional period or before finishing device payments. (Many carriers now waive strict 2-yr penalties, but device financing may still require completion.)
Initial Costs	Often just a small SIM card fee (sometimes free). No device deposit. For eSIMs, immediate. Prepaid may require a deposit for data packs (¥1,000–¥3,000).	May include an upfront "handset charge" if buying a new mobile phone (usually ¥0–¥5,500+), plus possibly a SIM activation fee (~¥3,300 on docomo/au/SoftBank, but often waived online). Device installment down-payments vary by plan.
Device Options	Bring-your-own-mobile phone (must be unlocked/SIM-free). Mobile virtual network operators sell only SIM cards – you use your existing device or buy unlocked separately. No device subsidies.	Bundled with devices: Carriers let you buy or finance smartphones/tablets with the contract. Devices often come with discounts/promotions (especially on MNP). Also eSIM options for compatible mobile phones.

How to Sign Up: Step-by-Step

1. Prepare your documents: Almost all mobile plans require proof of identity and visa status. For foreigners living in Japan, this means a valid Residence Card (在留カード) or Special Permanent Resident certificate. A passport may suffice for short-term prepaid SIM cards or at international counters. Some carriers also ask for a My Number card (personal ID), insurance card, or driver’s license as second ID. If you want to pay by bank transfer, have a Japanese bank account/debit card (known-name credit/debit or ATM card) ready.
2. Choose provider and phone plan: Decide which carrier/mobile virtual network operator fits your needs (see “Recommended Providers” below). Check that your mobile phone is SIM-unlocked and compatible with Japanese mobile networks. For eSIM-capable mobile phones, you can even use foreign eSIMs. It’s usually easiest to order online via the provider’s website (where some offer English forms) so you don’t struggle in a store.
3. Online Application: On the carrier’s or mobile virtual network operator’s site, select “SIM-only” or desired mobile plan. You will typically fill in your name, address, residence number, etc., upload photos of your Residence Card/passport, and choose payment method (credit card, etc.). For SIM-only, you might need to input your mobile phone’s IMEI (device ID). Review and submit the form. Note the appointment of contactable email is required so they can send SIM shipment info.
4. Receive and activate SIM card: The SIM card/eSIM kit will arrive by mail (or pick up at airport/office for some providers like Mobal). Insert the SIM card into your mobile phone and follow activation instructions (often just power on; or scan QR for eSIM). The carrier’s English support pages or included leaflet will guide setup. Once activated, you can dial or use data immediately.
5. Payment Setup: Ensure your payment method is active (e.g. credit card charge succeeded). For recurring phone plans, first month (or partial month) may be prorated. You’ll start paying monthly after activation.

Key documents summary: In practice, a Residence Card + credit card will cover most cases. Only passport alone (no residence card) may work with specialized prepaid/eSIM (Mobal allows passport-only sign-up).

Recommended Providers and Examples

Rakuten Mobile: Fourth carrier; offers the “Rakuten 最強プラン” unlimited data plan (0–3GB ¥1,078, 3–20GB ¥2,178, >20GB ¥3,278) with no data limit beyond that. No minimum contract and no cancellation fee. All calls/SMS via Rakuten’s app are free. Japanese online signup has English versions, and they accept credit cards, debit, bank transfer or even their Rakuten points. Device financing is optional. Ideal for heavy-data or budget users.

LINEMO (SoftBank sub-brand): Online-only SIM phone plan. Has 3GB/10GB/30GB tiers at ¥990/¥2,090/¥2,970 (plus 5-min calls on highest tier). LINE app usage is “data-free”, which is great if you use LINE a lot. No min term or cancellation fee. Accepts bank transfer and credit card. Good for light-to-moderate users (especially LINE users) who don’t need a mobile phone subsidy.

ahamo (Docomo): Online SIM-only service with 30GB for ¥2,970 or 110GB for ¥4,950, both including 5 minutes domestic calls. Comes with free global roaming data (30GB) in 82 countries, so excellent for frequent travelers. No contract term or cancellation fee. Japanese-only support, but widely available docs and predictable pricing.

Mobal: A foreigner-focused SIM card (on SoftBank mobile network). No Residency Card needed – you can even sign up before arrival and pick up at airports. Phone plans: 1GB/5GB/10GB/30GB for ¥1,650–¥4,378. Multilingual support (English/Chinese/Japanese) and flexible 1-month minimum. Useful if you lack Japanese credit: they accept PayPal/Alipay. Example: “5GB Plan” at ¥3,190 yields midrange data usage.

IIJmio: A popular mobile virtual network operator on docomo/au mobile networks. Offers a “Japan Travel SIM” prepaid (data-only, 30-day validity) that can be bought at airports and has English/Chinese support. For postpaid, IIJmio has low-cost “Giga Plan” (e.g. 5GB for ¥1,300, 20GB for ¥3,000) with voice option. Note: IIJmio’s monthly phone plans have support in Japanese only, so language-savvy users enjoy the low price.

Y!mobile: SoftBank’s sub-brand with nationwide coverage. Offers “Simple” phone plans (e.g. S/M/L) similar to LINEMO but with in-person stores. Only passport + residence card needed (no credit history checks). Stores in major cities often have English-speaking staff. Monthly fees are moderate (a few thousand yen). Good balance of price and reliability.

Others: Sakura Mobile, Japan Wireless, YOLO, etc. cater to foreigners with short-term SIM cards or pocket WiFi. Prepaid eSIMs (Airalo, etc.) exist for tourists but often at higher per-GB cost. Big carriers (docomo/au/SoftBank) can be used SIM-only as well (bringing your own mobile phone), but their basic phone plans tend to be pricier.

Examples: The cheapest unlimited data SIM card for a resident is Rakuten Mobile’s ~¥3,278 plan. The best-value mobile plan with English support might be Mobal’s 5GB plan (¥3,190) or Sakura Mobile’s prepaid SIM card. For prepaid vs postpaid: prepaid SIM cards cost more per GB and expire (e.g. IIJmio’s Japan Travel SIM is 30 days for ~¥3,000), whereas a postpaid SIM card (like Rakuten Mobile or Mobal) costs less per GB with no expiry but requires ongoing payment.

Tips for Foreigners

• Language barrier: Always check if the carrier has English-language info. Rakuten Mobile and LINEMO have English websites. Mobal/Sakura Mobile/YOLO have multilingual support. Larger carrier stores in Tokyo/Osaka often have English-speaking staff, but many small mobile virtual network operators are Japanese-only. Online signup (with translation tools) is often easier.
• Contract details: Read the fine print (最低利用期間, 解約金, 通信制限). Even “no contract” phone plans may throttle speeds after a data cap. For example, “no-term” SIM cards typically slow to 200kbps once you exceed your mobile plan’s data usage. Also check whether free domestic calls/SMS require an app. If canceling a contract plan, make sure the device is fully paid to avoid outstanding charges.
• Payment methods: If you lack a Japanese credit card, look for providers accepting bank debit cards, PayPal, Alipay or allow point payment (Rakuten points). Rakuten Mobile and some mobile virtual network operators allow bank transfer or Rakuten points.
• Where to sign: For SIM-only, online sign-up is recommended – it’s often faster and avoids spoken Japanese. If you go to a shop, major electronics retailers (Bic Camera, Yodobashi) sell many SIM-only cards (ask for “格安SIMカード”). Airport SIM shops and convenience stores also sell prepaid SIM cards.
• Keep your Residence Card updated: If your address on the card is outdated, some carriers will ask for a utility bill or resident certificate to prove your current address. Make sure all info matches.
• Bonus: Use a VoIP app (LINE/Messenger/Skype) to reduce call charges. Rakuten Mobile’s Link app makes domestic and even international calls free via data usage, which is a major saving.