Yes, Optus works in Japan. Japan is Zone 1 — on eligible Optus Choice Plus plans you get 5GB of data plus unlimited calls and texts for AUD$5 per day. A 10-day Japan trip costs AUD$50. A Travelren Japan eSIM for the same trip costs around AUD$12–18 depending on the plan. The Optus rate is competitive — here’s the honest break-even.
Travelren sells Japan eSIMs, so this comparison has stakes. Real numbers, and the cases where staying on Optus roaming makes genuine sense.
The quick answer
- Optus in Japan (Choice Plus plan): AUD$5/day, 5GB data, unlimited calls + texts. Zone 1.
- Optus in Japan (standard postpaid): AUD$10/day, 1GB data. Check My Optus before you leave.
- Travelren eSIM, 3GB / 30 days: approximately AUD$12
- Crossover ($5/day plan): eSIM cheaper from day 3 onward
- Crossover ($10/day plan): eSIM cheaper from day 2 onward
How Optus actually works when you land in Japan
Japan has three main carriers: NTT Docomo, SoftBank, and KDDI au. Optus routes to SoftBank as the primary roaming partner in Japan. Coverage across Tokyo, Osaka, Kyoto, Hiroshima, and Fukuoka is excellent — 5G in city centres, strong 4G LTE everywhere else including the Shinkansen between major cities.
NTT Docomo has marginally better rural coverage in mountain areas and northern Tohoku, but for the standard Aussie Japan itinerary (Tokyo, Kyoto, Osaka loop) SoftBank is indistinguishable in practice. Speeds are fast enough for Maps, Suica card top-ups, and video calls without issue.
Zone 1 day pass activates automatically on first data use. Optus sends an SMS confirmation with the daily charge. Days where you use hotel WiFi exclusively and don’t trigger any mobile data use aren’t charged.
Optus Zone 1 day pass — Japan detail
- AUD$5/day on Choice Plus plans (5GB data, unlimited calls + SMS)
- AUD$10/day on standard postpaid plans (1GB data, unlimited calls + SMS)
- Verify your rate in My Optus app before departure — it shows your specific entitlement
- Prepaid customers: different packs apply, check Optus website
What an eSIM costs for the same Japan trip
Travelren Japan eSIM plans (AUD as of May 2026):
- 1GB / 7 days: approximately AUD$4.60 — right for a short Tokyo weekend
- 3GB / 30 days: approximately AUD$12 — sweet spot for 1–2 weeks
- 10GB / 30 days: approximately AUD$22 — for heavy users or those working remotely
Break-even math
| Trip length | Optus $5/day | Optus $10/day | Travelren eSIM (3GB) |
|---|---|---|---|
| 2 days | AUD$10 | AUD$20 | AUD$12 |
| 5 days | AUD$25 | AUD$50 | AUD$12 |
| 10 days | AUD$50 | AUD$100 | AUD$12 |
| 14 days | AUD$70 | AUD$140 | AUD$12 |
On the $5/day plan, Optus is competitive for very short trips. From day 3 onward the eSIM pulls ahead. On the $10/day plan, the eSIM wins from day 2.
When Optus roaming is actually the right call
- One or two night stopover: If Japan is a brief stop between destinations, AUD$5–10 once or twice isn’t worth the eSIM setup overhead.
- $5/day plan and short trip: Three days in Tokyo for AUD$15 is genuinely reasonable if you’re on the Choice Plus rate.
- Phone not eSIM compatible: Check your device. Some older or carrier-locked phones don’t support eSIM.
- Need your Optus number for 2FA: Japanese services like Google Pay Japan or banking apps don’t need your Aussie number — but your own bank might SMS you. Keep Optus for calls, run the eSIM for data.
The dual SIM setup for Japan
If you want cheap data without losing your Optus number: install a Japan eSIM as your data line, leave the Optus SIM installed for calls and SMS. In iPhone Settings → Mobile Service, set the eSIM as Primary for data. Your Optus number stays active and reachable without triggering a data day — you only pay Optus if you actually make or receive a call.
Setting up a Japan eSIM
- Buy before you leave Australia — QR code is emailed instantly.
- Install on Australian WiFi before departure.
- Set as default data line in phone settings.
- Land in Japan, enable data — connects to SoftBank or NTT Docomo automatically.
Common questions
Does Optus work on the Shinkansen between Tokyo and Osaka?
Yes. SoftBank has strong coverage along the Tokaido Shinkansen route. Expect brief signal drops in tunnels — this applies to all carriers and eSIMs in Japan.
Can I use Optus in Japan without activating a day pass?
Technically yes, but standard pay-as-you-go rates are AUD$1.50–4/minute for calls and AUD$1–2/MB for data. Turn off mobile data on arrival and only enable it when you have a day pass active.
Does the $5/day Optus pass include tethering in Japan?
Yes. The 5GB allowance covers both direct use and hotspot sharing.
Will my Suica card app work on a Japan eSIM?
Suica on iPhone uses NFC, not cellular data. It works regardless of which SIM or eSIM you’re using. Internet is only needed to top up the card balance.