Japan · Travel eSIM
Japan eSIM for UK travellers
Data plans for Japan that connect to KDDI (au), NTT docomo, SoftBank and Rakuten Mobile. Install one before you fly from the UK; plans and prices are Computatus eSIM's, checked 31 October 2026.
At a glance
- Networks
- Plans connect to KDDI (au), NTT docomo, SoftBank and Rakuten Mobile. 5G is listed on KDDI (au), NTT docomo, SoftBank and Rakuten Mobile.
- Plans from
- US$1.86 (about £1.40) for 1GB · 1 day.
- For a week
- 5GB · 30 days for US$5.02 (about £3.78) covers a week of moderate use.
- Your UK number
- Keep your UK SIM on for calls and texts; the eSIM carries your data.
eSIM plans for Japan
Computatus eSIM plans for Japan, a spread of data amounts and lengths. Buy one here: you pay on the secure Computatus eSIM checkout and come back to CogniTel once the payment is confirmed.
| Plan | Price | In pounds | Buy |
|---|---|---|---|
| 1GB · 7 days | US$1.95 | about £1.47 | Buy |
| 2GB · 15 days | US$2.23 | about £1.68 | Buy |
| 3GB · 15 days | US$3.16 | about £2.38 | Buy |
| 3GB · 30 days | US$3.35 | about £2.52 | Buy |
| 5GB · 30 days | US$5.02 | about £3.78 | Buy |
| 10GB · 30 days | US$8.74 | about £6.58 | Buy |
| 20GB · 30 days | US$15.25 | about £11.48 | Buy |
| 50GB · 30 days | US$31.62 | about £23.80 | Buy |
CogniTel is a reseller of Computatus eSIM. Payment, delivery and support are by Computatus eSIM. Prices are in US dollars, as charged at checkout; pound figures are approximate, at US$1 = £0.75 (28 October 2026).
One eSIM for Japan and nearby countries
These regional plans include Japan, for trips that cross borders:
- Japan & South Korea 2 countries · 1GB · 7 days: US$2.01 (about £1.51) Buy
- China mainland & Japan & South Korea 3 countries · 1GB · 1 day: US$3.27 (about £2.46) Buy
- Asia 12 countries · 500MB · 1 day: US$2.47 (about £1.86) Buy
- Asia 14 countries · 1GB · 1 day: US$1.93 (about £1.45) Buy
- Asia 19 countries · 500MB · 1 day: US$2.98 (about £2.24) Buy
- Asia-20 20 countries · 1GB · 7 days: US$4.69 (about £3.53) Buy
How much data you need in Japan
Rough guides for a phone used abroad, with the cheapest plan here that covers each.
| Trip | Light use | Moderate use |
|---|---|---|
| A long weekend (3 days) | 1 GB 1GB · 7 days: US$1.95 | 3 GB 3GB · 15 days: US$3.16 |
| A week | 2 GB 2GB · 15 days: US$2.23 | 5 GB 5GB · 30 days: US$5.02 |
| A fortnight | 4 GB 5GB · 30 days: US$5.02 | 10 GB 10GB · 30 days: US$8.74 |
| A month | 8 GB 10GB · 30 days: US$8.74 | 20 GB 20GB · 30 days: US$15.25 |
Mobile networks in Japan
Computatus eSIM plans for Japan connect to local networks: KDDI (au), NTT docomo, SoftBank and Rakuten Mobile. Your phone picks the strongest signal among those the plan lists.
Setting it up
Check your phone. It must support eSIM and be unlocked. On an iPhone, Settings > Mobile Data shows Add eSIM; on Android, look under SIM or Network settings.
Install before you fly. Open the link or scan the QR code from the email while you still have Wi-Fi at home. The plan's days start when it first connects abroad.
Switch data on arrival. Set the eSIM as your line for mobile data and turn its data roaming on. Leave your UK SIM on for calls and texts.
Coming home. Switch mobile data back to your UK SIM. You can delete the travel eSIM once its plan has ended.
Japan eSIM: questions
Which eSIM plan do I need for a week in Japan?
For a week of maps, messages, social media and some video, about 5 GB is enough: 5GB · 30 days costs US$5.02 (about £3.78).
Which networks does a travel eSIM use in Japan?
Computatus eSIM plans for Japan use KDDI (au), NTT docomo, SoftBank and Rakuten Mobile.
Is there 5G in Japan?
Yes: plans list 5G on KDDI (au), NTT docomo, SoftBank and Rakuten Mobile. On a phone without 5G the same plans work on 4G.
Can I keep my UK number while I use an eSIM?
Yes. Most phones hold your UK SIM and an eSIM at once: keep the UK SIM on for calls and texts, including your bank's security codes, and use the eSIM for data.
When should I buy and install the eSIM?
Before you travel, while you have Wi-Fi at home: installing takes a few minutes, and the plan's days only start when it first connects in Japan.