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# How to Buy a Japan eSIM with USDT or Card in the Fizen App (2026): Four Taps, Prices, GB, Video Guidance
- URL: https://blog.fizen.io/how-to-buy-japan-esim-in-app-2026/
- Published: 2026-09-23T18:52:19.000Z
- Updated: 2026-09-23T19:20:01.000Z
- Description: For the traveller who has already decided to buy and wants the screens, the plan and the price. Four taps, a 32 second video, and the one timing mistake that starts your plan early.
- Author: Quinn Dao
- Tags: eSIM, Travel & Nomad, esim-city

**Quick answer:** Open the app, tap eSIM, search Japan, pick a plan, pay with USDT, card, Apple Pay or Google Pay. For most trips the 10 GB Japan plan valid 15 days at US$17.69 is the one to take, checked 24 September 2026, and it roams on KDDI across 4G and 5G.

**Key takeaways**

- **Four taps, not a QR code.** eSIM tab, search Japan, pick the plan, pay. After payment an activation link installs the eSIM itself, per the Fizen eSIM docs.
- **The network is KDDI, on 4G and 5G**, for every Japan country plan. Fixed plans slow to 384 kbps once the data is used, which still loads maps and messages but not video.
- **Take the longer validity window.** 10 GB valid 7 days is US$17.18 and the same 10 GB valid 15 days is US$17.69, so 51 cents buys another week of flexibility. Checked 24 September 2026.
- **Buy before you fly, install before you fly, switch on after you land.** The docs are explicit: installing a plan while you are already inside its coverage can start the validity clock early.

This is the page for someone who has already decided. You want the screens, the plan that fits a Japan trip and what it costs today, not another comparison of eSIM providers. Everything below comes from the Fizen eSIM docs and the live plan catalogue, checked on 24 September 2026.

## Which Japan plan should I buy?

Every Japan country plan roams on **KDDI, 4G and 5G**. The choice is only about how much data you need and how long you want the plan to stay valid. These are the live prices on 24 September 2026.

| Your trip                       | Plan              | Total    | Per GB            |
| ------------------------------- | ----------------- | -------- | ----------------- |
| Weekend, maps and messaging     | 5 GB, 7 days      | US$10.12 | US$2.02           |
| One to two weeks, normal use    | 10 GB, 15 days    | US$17.69 | US$1.77           |
| Two weeks, heavy maps and video | 20 GB, 15 days    | US$24.32 | US$1.22           |
| A month, working remotely       | 20 GB, 30 days    | US$25.33 | US$1.27           |
| No thinking about data at all   | Unlimited, 7 days | US$27.50 | capped at 10 Mbps |

A normal Japan day is maps in the morning, a translation app in front of a menu, LINE with the people you are travelling with and a train app. That lands between 0.6 and 1 GB a day. Ten gigabytes covers a fortnight for most people, and the 15 day window means a delayed flight does not strand you.

## How do I buy it in the app, step by step?

Check the phone first. In the app's eSIM section there is a device check, or dial **\\\*#06#** and look for an EID. An eSIM you have not installed can still be returned; once installed it cannot.

1. Open the Fizen app and tap **eSIM** on the home screen.
2. Type **Japan** in the search. Country plans and the wider regional plans both appear.
3. Pick the plan by data amount and validity, using the table above.
4. Pay with **USDT from your wallet balance**, or by **card, Apple Pay or Google Pay**. Card details go to Stripe, and Fizen never stores the number.

Twenty eight seconds of what this actually buys you: landing at 11pm, online at 11:01, paid in USDT.

New to the app? The US$10 eSIM welcome credit applies by itself the first time you open the eSIM tab. There is no code to enter, it is in-app only, and it is valid for 12 months.

## When should I install it, and when do I switch it on?

This is the only step where the order matters. Buy and install at home on trusted Wi-Fi, in the days before departure. Then leave the line off until the wheels touch down at Haneda, Narita or Kansai.

1. After payment you get an **activation link** by in-app notification and email. Open it on the phone that will carry the eSIM.
2. Confirm the install prompt when your phone asks to add the eSIM.
3. After landing, turn on **Data Roaming** for the eSIM line in Settings, under Cellular or Mobile.

The reason for the wait is in the docs: if the plan also covers the country you are standing in, installing and enabling it early can start the validity clock before your trip does.

## What happens when the data runs out?

Japan fixed plans drop to **384 kbps** when the bucket is empty. That is enough for LINE messages, a train app and a map tile that eventually loads. It is not enough for a video call, and it is not enough to stream anything.

Plans cannot be topped up, so size for the whole trip rather than the first few days. The unlimited plan has the opposite shape: no volume limit, but a **10 Mbps ceiling**, which carries a video call comfortably and will not carry a 4K stream.

## Is a Japanese tourist SIM cheaper?

Sometimes, and the honest answer depends on the counter you walk up to. Airport counters at Narita, Haneda and Kansai sell visitor SIMs and pocket Wi-Fi rentals, usually with a passport, a form and a queue after a long-haul flight. Pocket Wi-Fi adds a device to charge and return before your flight home.

The eSIM wins on the arrival hour, because it is already installed when you land, and on the return, because there is nothing to hand back. A local SIM can win on price for a long stay with heavy data. Compare the counter price per gigabyte against the table above before you commit.

## Frequently asked questions

#### Does a Japan eSIM give me a Japanese phone number?

No. These are data only plans. Keep your home SIM active in the other slot if you need SMS codes from your bank.

#### Which network does the Japan plan use?

KDDI, on 4G and 5G, for every Japan country plan. The South-Eastern Asia regional plan uses NTT DoCoMo on 5G instead and costs more for Japan alone.

#### Can I pay in USDT?

Yes, straight from your Fizen wallet balance, with no card or bank account. Card, Apple Pay and Google Pay also work at checkout.

#### What if my phone does not support eSIM?

Dial \*#06# and look for an EID, or use the device check in the app's eSIM section. Without an EID the plan will not install, so check before buying.

#### Can I get a refund if my plans change?

An eSIM you have not installed yet can usually be returned, subject to the plan, and an installed one cannot. If a verified Fizen-side fault stops it working, the commitment is a free replacement for the length of the trip.

![](https://storage.ghost.io/c/04/ee/04eee3a6-7d95-474c-80a5-48f84338363b/content/images/2026/09/how-to-buy-japan-esim-in-app-2026-6.png) 

#### Land in Japan already connected

Japan plans roaming on KDDI across 4G and 5G, bought in the app with USDT, card, Apple Pay or Google Pay. Data only, installed before you fly. New users get the US$10 eSIM credit automatically in the app's eSIM tab, no code, valid 12 months. Not offered to US Persons.

[Buy the Japan eSIM in the app](https://link.fizen.io/s/2EtJn-lYe7?ref=blog.fizen.io) 

### Terms and conditions

- **Information only.** This article explains how to buy mobile data for a trip to Japan. It is not an offer or sale of any product or service, and it is not financial, legal or tax advice.
- **For readers in the United States.** This article provides information only. It is not an offer, solicitation or sale of any product or service, and it is not financial, investment, legal or tax advice. Fizen is not offered to US Persons.
- **Independent.** Fizen is not affiliated with, endorsed by or a partner of KDDI, NTT DoCoMo, Apple, Google, LINE or any airport operator. Prices and coverage change, and the figures here carry the date they were checked.
- **Full terms.** See the Master Terms of Use, Privacy Policy and Disclaimer on the Fizen website.

### Sources

- [Fizen Docs: How to buy an eSIM](https://docs.fizen.io/help-center/fizen-esim/how-to-buy-an-esim?ref=blog.fizen.io)
- [Fizen Docs: Purchase and activate an eSIM](https://docs.fizen.io/help-center/fizen-app/faq/purchase-and-activate-an-esim?ref=blog.fizen.io)
- [Fizen Docs: Supported devices](https://docs.fizen.io/help-center/fizen-esim/supported-devices?ref=blog.fizen.io)
- [Fizen Docs: Welcome credit](https://docs.fizen.io/help-center/fizen-esim/welcome-credit?ref=blog.fizen.io)
- [Fizen Docs: Trip guarantee and returns](https://docs.fizen.io/help-center/fizen-esim/trip-guarantee?ref=blog.fizen.io)
- [Fizen Docs: Card payments](https://docs.fizen.io/help-center/fizen-esim/card-payments?ref=blog.fizen.io)
- [Fizen: How to buy eSIM with Fizen Super App (video)](https://www.youtube.com/watch?v=3LREXG0F0Ts&ref=blog.fizen.io)

Plan prices and steps checked on 24 September 2026.

### Related reading

- [Best eSIM for Japan: the country guide](https://blog.fizen.io/best-travel-esim-for-japan-2026/)
- [Best eSIM for Tokyo](https://blog.fizen.io/best-esim-tokyo-2026/)
- [Internet in Japan: SIM, eSIM and Wi-Fi](https://blog.fizen.io/internet-in-japan-2026/)
- [One eSIM for Japan and South Korea](https://blog.fizen.io/esim-for-japan-and-south-korea-trip-2026/)
- [Which phones support eSIM](https://blog.fizen.io/which-phones-support-esim-in-2026-the-complete-compatibility-list/)