Docomo, KDDI or SoftBank? 3 Japanese Carriers Compared for Speed

[DJB | LINE GO exclusive airport transfer discount $300 ✈️]
From now through 2024/04/14, order any DJB data SIM to get 5% off
plus an exclusive LINE GO airport transfer discount of $300

The discount code is right in this article! Click to unlock it >> https://lihi2.com/eb4PI
Let LINE GO take you around the world with efficient transfers 🚙

Introducing Japan's carriers

NTT DOCOMO

NTT DOCOMO is a publicly listed Japanese carrier with over 20 years of operation, the longest history and the largest user base among Japan's carriers — comparable to Chunghwa Telecom in Taiwan. Its coverage is comprehensive, with signal reachable almost anywhere in Japan, making it a genuinely trustworthy carrier.

AU KDDI

AU KDDI was formed from the merger of major Japanese carrier KDDI and the AU brand's telecom services. Signal indoors or in certain areas is relatively weaker, and it ranks second by scale among Japan's three major carriers.

SOFTBANK

SOFTBANK is a major Japanese mobile carrier, with the group also spanning telephony, internet, and technology services. Coverage is stronger in big cities, though somewhat less stable in mountainous or rural areas — overall, a stable, quality carrier.

An essential data SIM for exploring Japan

DJB Global Data offers Japan SIM cards with different data plans, letting you choose the right option for anywhere from 1 to 30 days based on your needs — buying exactly as many days as you're travelling is genuinely convenient~

Flexible duration, unlimited data plan → DJB Daijobu Unlimited card
Flexible duration, low-to-medium data plan → DJB Daijobu Travel card
Unlimited data plan → DJB Daijobu Play card

If your phone supports eSIM, check out -> DJB's eSIM section

FAQ about travel data SIMs

Can DJB's Japan data SIM make phone calls?

Whether it's DJB's Daijobu Unlimited, Daijobu Travel, or Daijobu Play card, all are pure data SIMs, with no calling function or phone number — use apps like Skype, LINE, or Facebook Messenger for calls instead.

Will swapping in a new SIM card affect the data already on my phone?

Swapping SIM cards won't affect your existing LINE, Facebook, or other app content and data, unless you're using an older-style phone that stores certain data directly on the SIM card — no need to worry otherwise.

Can someone who isn't tech-savvy use this?

Absolutely. DJB's Japan data SIMs are plug-and-play by default, and based on our experience serving hundreds of thousands of customers, roughly 95% of phones connect and configure automatically once the SIM is inserted. For the rest, simply follow the steps included in the packaging to check your connection and get online.

Is "unlimited" advertised online really unlimited with no throttling?

When shopping for a data SIM, if the listing mentions a "fair usage policy," that means the carrier restricts heavy users, and you may notice slower speeds or lose connectivity. So any card marked with this policy will be throttled at some point, regardless of whether it's advertised as "no throttling" — and the Daijobu Unlimited card is subject to this policy too. That said, the Daijobu Play card has an exclusive partnership agreement that guarantees users are exempt from this policy, with truly no throttling, letting you explore Japan without a worry.

Does Japan offer free hotspot Wi-Fi or free SIM cards?

Yes, but free hotspot Wi-Fi in Japan is genuinely not very practical — it's not available everywhere you go, and it tends to be unstable. Everyone we know who travels to Japan often has flat-out ruled out relying on it. You can also find a few plans online offering free SIM cards, but the data allowance and connection quality tend to fall short — we still recommend buying your own data plan for peace of mind when travelling or working abroad.

A friendly summary

The number of Taiwanese travellers visiting Japan keeps growing year after year — great sightseeing, great food, great shopping, and affordable flights have made a Japan trip a must on every Taiwanese traveller's bucket list. And when you're there, internet access is absolutely essential — whether you're checking a map, searching for food, or checking in and sharing updates, nothing works without a connection. No need to worry now — we've put together a handy rundown of Japan's three major carriers, giving everyone a basic understanding of Japan's telecom landscape so you can pick the plan that suits you best. Finally, Daijobu wishes everyone a wonderful trip to Japan~

Popular destinations