Choosing a mobile plan is one of the first things you need to sort out after arriving in Japan. With so many options available, and most information written in Japanese, it can feel overwhelming. This guide breaks down the Japan mobile network providers comparison—Docomo, au, SoftBank, and Rakuten—so you can understand your choices clearly and pick the plan that actually works for your situation.
The Four Main Mobile Networks in Japan
Japan has four major mobile network operators, often called MNOs. These companies own and operate the physical network infrastructure—the towers and cables that carry your calls and data across the country. Every other mobile provider (called an MVNO) rents space on one of these networks to offer their own, often cheaper, plans.
Docomo
Docomo is Japan's largest carrier by number of subscribers. Its network covers the widest geographic area, including rural areas and mountainous regions where other networks can be weaker. If you travel frequently around Japan or live outside a major city, Docomo's coverage can be a real advantage. Docomo also offers plans under its budget sub-brand, ahamo, which provides a straightforward data plan at a lower price point. Check Docomo's official site for the latest plan details and pricing.
au (by KDDI)
au is operated by KDDI and is the second-largest carrier in Japan. Its network is strong across urban areas and generally competitive with Docomo in terms of rural coverage. au offers budget options through its sub-brand UQ Mobile, which is popular among cost-conscious users. If you already use certain services linked to KDDI or are considering a bundled home internet plan, au may be worth exploring. Always confirm current plans and pricing on the official au or UQ Mobile website.
SoftBank
SoftBank is the third of the traditional "big three" carriers. Its network performs well in urban centres and is widely used throughout Japan. SoftBank runs Y!mobile as its budget sub-brand, offering lower monthly costs while still running on the SoftBank network. SoftBank has also historically been active in international partnerships, which may be relevant if you need good international roaming options. Check the official SoftBank or Y!mobile site for up-to-date plan information.
Rakuten Mobile
Rakuten Mobile is the newest of the four major networks, having launched its own infrastructure more recently. Its coverage has been expanding rapidly, especially in urban areas. Rakuten Mobile's pricing is generally competitive and it integrates well with the broader Rakuten ecosystem (points, shopping, banking). However, its rural coverage is still catching up to the big three, so if you live or work outside major cities, it is worth checking the coverage map for your specific area before signing up.
Why the Big Three Can Be Tricky for Foreigners
Signing up directly with Docomo, au, or SoftBank can be difficult if you have just arrived in Japan. Here is why:
- Japanese credit card required: Most direct contracts with the big three require a Japanese credit card for billing, which takes time to obtain as a newcomer.
- Japanese bank account needed: Some payment methods require a Japanese bank account, another thing that takes a few weeks to set up after arrival.
- Language barrier: In-store staff and contracts are primarily in Japanese, which can make the process stressful if your Japanese is limited.
- Long contracts and cancellation fees: Some plans come with conditions around contract length or early cancellation, so read the terms carefully.
This does not mean you can never use these carriers—many foreign residents do—but it is worth knowing these hurdles exist before you walk into a store.
What You Generally Need to Get a SIM in Japan
Regardless of which carrier you choose, you will typically need the following documents for a contract SIM:
- A valid residence card (在留カード, Zairyu Card)
- A registered Japanese address
- A payment method (Japanese credit card or bank account for most carriers)
- A compatible unlocked smartphone
Requirements can vary between providers, so always confirm what each carrier asks for on their official website before visiting a store or applying online.
Foreigner-Friendly Alternatives Worth Knowing
If you have just arrived and do not yet have a Japanese credit card or bank account, there are services designed specifically for foreign residents. GTN Mobile accepts your residence card, offers multilingual support, and does not require a Japanese credit card—making it a practical option for newcomers. Mobal is another option that requires neither a Japanese credit card nor a Japanese bank account, and provides English-language customer support.
These services operate as MVNOs, meaning they use one of the major networks described above to provide coverage. Check which network each MVNO runs on, as this affects the coverage you will receive.
For short stays or as a stopgap right after landing, prepaid SIMs and eSIMs (available at airports and online) let you get connected immediately without any contract. They are not the cheapest long-term option, but they give you breathing room while you sort out a permanent plan.
Key Things to Compare When Choosing a Plan
Whether you go with a major carrier or an MVNO, use this checklist when comparing plans:
- Monthly price: What is the total monthly cost including taxes? Confirm on the official site as prices change.
- Data allowance: How much data do you get, and what happens when you exceed it—does speed drop or do you pay extra?
- Voice calls included: Is it a data-only plan, or does it include calls? Do you need a Japanese phone number?
- Payment method accepted: Do you need a Japanese credit card or bank account, or are other options available?
- Contract length and cancellation conditions: Is there a minimum period or an early cancellation fee?
- Language support: Is customer service available in English or your language?
- Coverage in your area: Check the official coverage map for where you live, work, and travel most.
Quick Comparison Overview
| Carrier | Network Size | Budget Sub-Brand | Foreigner-Friendly? |
|---|---|---|---|
| Docomo | Largest, widest rural coverage | ahamo | Possible, but Japanese credit card usually needed |
| au (KDDI) | Large, strong urban and regional | UQ Mobile | Possible, but Japanese credit card usually needed |
| SoftBank | Large, strong urban coverage | Y!mobile | Possible, but Japanese credit card usually needed |
| Rakuten Mobile | Growing, strongest in cities | — | Competitive pricing; check rural coverage first |
| GTN Mobile / Mobal | MVNO (uses major networks) | — | Yes—designed for foreign residents |
This table is a general guide. Plans, prices, and conditions change regularly. Always check the latest information on each provider's official website before making a decision.
Summary: Finding the Right Network as a Foreign Resident
Japan's mobile landscape gives you plenty of options, but the right choice depends on your specific situation—how long you have been in Japan, what documents you have, where you live, and how much data you need. The big three carriers (Docomo, au, SoftBank) offer excellent coverage and a range of price points through their sub-brands, but can require a Japanese credit card and bank account that take time to set up. Rakuten Mobile is worth considering if you live in an urban area and want competitive pricing. If you are newly arrived or want English-language support, foreigner-friendly MVNOs like GTN Mobile and Mobal are practical starting points.
Start by checking coverage maps for your area, then compare what each plan actually requires in terms of documents and payment. Take your time, confirm everything on official sites, and do not be afraid to start with a prepaid SIM while you get settled. Getting connected in Japan is very achievable—you just need the right information to get started.