Disclaimer: The prices and information presented on this page reflect a snapshot at the time of research and may change at any time without prior notice.
Tarkan
22 March 2026
Optus roaming in Japan is one of the more straightforward options for Australian travellers. If you're on a Choice Plus plan, the $5 daily roaming kicks in the moment you use data, make a call, or send a text after landing at Narita, Haneda, or Kansai. You get 5 GB of data, unlimited calls, and unlimited texts for each 24-hour period. That's a solid deal compared to Telstra's $10 Zone 2 Day Pass. But not every Optus customer is on Choice Plus, and the alternatives cost more while delivering less. If you're on a standard postpaid plan, the Roaming Pass drops your daily allowance to 1 GB for $10. Prepaid customers get an even tighter deal. This guide covers every Optus roaming option for Japan, including what actually happens when your 5 GB runs out, and when a travel eSIM with full-speed local data makes more financial sense.
Optus offers different roaming products depending on which plan you're on, and the gap between the best and worst option is significant. Japan falls into Optus's Zone 1 category, which covers 150+ destinations and qualifies for all roaming add-ons.
Choice Plus plans (Daily Roaming at AUD $5/day): This is the best deal. You get 5 GB of data, unlimited standard calls, and unlimited texts for each 24-hour period. The 24 hours start from the moment you first use your phone (data, call, or text), not from midnight. If you burn through 5 GB before the 24 hours are up, Optus automatically adds another 5 GB and charges another $5. There's no speed throttle during the allowance. Daily Roaming is auto-enabled on Choice Plus plans, so there's nothing to activate before departure.
Other postpaid plans (Roaming Pass at AUD $10/day): If you're not on Choice Plus, you get the Roaming Pass instead. Same 24-hour structure, but only 1 GB of data for $10. That's double the price and one-fifth the data compared to Daily Roaming. Unlimited calls and texts are still included. For data-heavy use in Japan, this becomes expensive quickly.
Standard Roaming (no pass active): If no add-on is enabled, Optus charges standard rates: AUD $1 per minute for calls and $1 per MB for data. At those rates, a single Google Maps session could cost $20-$50. Always verify that a roaming add-on is active before you travel.
Prepaid plans (Flex Plus): Optus prepaid customers can purchase roaming packs. The daily option gives you 1 GB, 100 texts, and 100 minutes for $5. The 7-day pack offers 7 GB, 700 texts, and 700 minutes for $35. Both are Zone 1 only. These packs are available through the My Optus app and activate immediately upon purchase.
The Choice Plus $5/day deal is genuinely competitive. At 5 GB per day, most travellers won't hit the cap unless they're streaming video or uploading large files. The auto-top-up at $5 per additional 5 GB is also reasonable compared to Telstra's overage rates. The problem is that this pricing is exclusive to Choice Plus plans. Everyone else pays significantly more for less data.
Choice Plus customers: nothing to do. Daily Roaming is automatically enabled on all Choice Plus plans. When you land in Japan and use your phone, the $5 charge activates for the first 24-hour period. You'll receive a confirmation SMS from Optus confirming that roaming is active and which local network you're connected to.
Other postpaid customers: check the My Optus app. Open the app, go to Services, then Settings, and verify that International Roaming is toggled on. If the Roaming Pass is active, you'll be charged $10 per day when you use your phone in Japan. If it's not active and you haven't enabled Standard Roaming, your phone won't connect to data abroad.
Prepaid customers: buy a roaming pack before landing. Open the My Optus app or visit the Optus website to purchase a daily or 7-day roaming pack. Packs activate immediately, so purchase just before departure or immediately after landing via Wi-Fi. Your prepaid balance must have sufficient credit to cover the pack cost.
Enable data roaming on your phone. On iPhone: Settings, Cellular, Cellular Data Options, Data Roaming. On Android: Settings, Connections, Mobile Networks, Data Roaming. This step is required regardless of your plan type.
Unused data expires every 24 hours. There's no rollover. If you pay $5 for 5 GB and only use 2 GB, the remaining 3 GB disappears when the next 24-hour period starts. Plan accordingly if you have data-intensive days (sightseeing with lots of photo uploads) versus lighter days (museums with Wi-Fi).
Optus Daily Roaming on Choice Plus is solid for short trips. But there are scenarios where a travel eSIM is the smarter choice:
You're not on a Choice Plus plan. The Roaming Pass at $10/day for 1 GB is expensive. A 10-day trip costs $100 in roaming alone, and you'll likely overshoot 1 GB multiple times. A travel eSIM with a larger data pool at a fixed prepaid cost eliminates daily arithmetic entirely.
You're staying more than 10 days. Even on Choice Plus at $5/day, a two-week trip is $70, and a three-week trip is $105. The daily charge adds up, and the 5 GB per day doesn't roll over. A travel eSIM with a fixed data allocation for the entire trip can be more cost-effective for longer stays.
You need data on multiple devices. Optus roaming charges per device. If you're travelling with a partner and both need connectivity, that's $10/day minimum on Choice Plus or $20/day on Roaming Pass. Individual eSIMs per device provide dedicated data pools without the daily multiplier.
You've had issues with the 24-hour auto-rollover. User reports on Australian forums mention that Optus Daily Roaming doesn't always auto-renew smoothly after the first 24 hours. Some travellers have had to contact Optus support to restart the service, which is inconvenient when you're navigating a foreign country. A travel eSIM with a multi-day data plan avoids this rollover mechanism entirely.
Japan consistently ranks as one of the top destinations for Australian travellers. The flight from Sydney to Tokyo is roughly 9 hours, and the time zone difference is minimal (1-2 hours depending on daylight saving). But the data demands of a Japan trip catch many Australians off guard. Google Maps is essential because Japanese addresses rarely follow a logical numbering system. Google Translate's camera feature is the only way to decipher most restaurant menus. Train apps like Navitime run constantly because the rail system, while incredible, has transfer patterns that are difficult to memorise.
Optus Daily Roaming at $5/day for 5 GB handles all of this well for a week or so. But the data expires every 24 hours with no rollover, and the daily charge applies whether you use 100 MB or the full 5 GB. A TurkSIM Japan eSIM gives you a fixed data pool for your entire trip, connecting directly to NTT Docomo and SoftBank at local 4G LTE speeds. No daily reset, no expiring data, no auto-top-up surprises.
The dual-SIM setup keeps your Optus number active for Medicare callbacks, bank verification codes, and incoming calls via Wi-Fi calling. The eSIM handles all data. You land at Narita, the eSIM connects to NTT Docomo, and you're navigating the Narita Express into central Tokyo within minutes. From Shibuya's scramble crossing to Kyoto's bamboo grove, your data runs on Japan's own network infrastructure rather than through a roaming intermediary.
For Roaming Pass customers paying $10/day for 1 GB, the equation tilts even further. Ten days of Roaming Pass costs $100 for a total of 10 GB (non-rollover). A TurkSIM Japan eSIM provides a comparable or larger data allocation at a fraction of that cost, with the data pool lasting your entire trip rather than resetting daily.
Yes. Japan is a Zone 1 destination for Optus, which means all roaming add-ons (Daily Roaming, Roaming Pass, and Prepaid packs) are available. Your phone connects to NTT Docomo or other local partner networks automatically when you arrive. Both postpaid and prepaid Optus customers can use roaming in Japan.
It depends on your plan. Choice Plus customers pay AUD $5 per day for 5 GB with unlimited calls and texts. Other postpaid customers pay $10 per day for 1 GB via the Roaming Pass. Prepaid customers can buy a daily pack for $5 (1 GB, 100 calls, 100 texts) or a 7-day pack for $35 (7 GB). Without any add-on, standard rates of $1/MB and $1/min apply.
No. Both Daily Roaming and Roaming Pass data expires at the end of each 24-hour period. If you use 2 GB out of your 5 GB allowance, the remaining 3 GB is lost when the next period starts. There is no way to carry unused data forward.
Optus automatically adds another 5 GB and charges an additional AUD $5 to your account. This auto-top-up happens without notification, so monitor your usage through the My Optus app if you want to avoid extra charges. The additional 5 GB expires at the same time as your original 24-hour window.
Yes. Most modern smartphones support dual SIM (physical SIM and eSIM). Keep your Optus SIM active for your Australian number and calls, while the travel eSIM handles data through local Japanese networks. Set the eSIM as your primary data line in phone settings and turn off data roaming for your Optus SIM to prevent accidental charges.
Optus primarily connects to NTT Docomo in Japan, which is the country's largest carrier by network footprint. Your phone may also connect to SoftBank or au (KDDI) depending on signal strength at your location. You can manually select a preferred network in your phone's settings if needed.
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