Ubigi vs ZenSim Japan eSIM: Which Is Better?

Ubigi Japan eSIM review: the short version

Ubigi is a long-running travel eSIM brand, and its Japan eSIM pops up on plenty of shortlists for Tokyo, Osaka and Kyoto trips. It's run by Transatel, a French telco owned by Japan's NTT group, so it knows its way around Japanese networks. The plans work, the brand is legit, and for a lot of travellers that's where the research stops.

It's worth digging a little deeper though, because the details matter in Japan. Ubigi's unlimited Japan plan comes with a 60GB cap for the whole month, while ZenSim's unlimited gives you 3GB of high-speed data every day that resets at midnight. On the 30 day plans most Aussies buy, ZenSim also comes in cheaper in Aussie dollars across the board, from 10GB right up to unlimited. Here's how the two stack up, including where Ubigi does a good job.

Is Ubigi a good eSIM for Japan?

Ubigi is a solid option, so let's give credit where it's due:

• A well-established brand backed by a major telco group
• A good spread of data plans, including 25GB and 50GB sizes
• Unlimited hotspotting, so you can share data with a laptop or tablet
• Coverage on strong Japanese networks in the cities and along the Shinkansen lines

And here's where it falls short for a lot of Japan travellers:

• Its unlimited plan has a 60GB monthly cap that doesn't reset, so a few big days early in your trip eat into the rest of it
• In Aussie dollars, it's pricier than ZenSim on every 30 day plan we compared
• A 4.1/5 customer rating, behind ZenSim's 4.9/5 from 442 reviews on ProductReview.com.au
• Support is built for a global audience rather than Aussie travellers in a hurry

If you want a reliable data pack and you're happy managing your usage across the month, Ubigi does the job. If you want a cheaper plan, a daily allowance that resets every night and quick help on WhatsApp, ZenSim is the better fit.

Is Ubigi's unlimited Japan plan really unlimited?

Not quite. Ubigi's unlimited Japan plan has a fair use limit of 60GB for the month, and once you've burned through it, that's your lot. It behaves more like a big 60GB pack than truly unlimited data, which matters if you're streaming on the Shinkansen or hotspotting a laptop for work in the first week of your trip.

ZenSim's unlimited plan works differently. You get 3GB of high-speed data every day, and if you go over, speeds drop to 1Mbps until midnight, which is still plenty for Google Maps, LINE, WhatsApp and booking your next ramen stop. Then it resets and you're back to full speed the next morning. Over 30 days that's up to 90GB of high-speed data against Ubigi's 60GB, and a heavy day in Shibuya never steals from the rest of your trip. Hotspotting is unlimited on both, though on ZenSim the 3GB daily allowance is shared across every device connected to your hotspot.

Ubigi vs ZenSim Japan prices and features

Here's how the two compare on their 30 day Japan plans, using regular Aussie dollar prices rather than flash sales (checked September 2026). Ubigi doesn't sell 20GB or 40GB in Japan, so we've compared its nearest sizes, 25GB and 50GB.

The gap is biggest in the middle of the range. ZenSim's 20GB plan is A$20 cheaper than Ubigi's 25GB, and 40GB is A$28 cheaper than Ubigi's 50GB, which is where most travellers on a two to four week Japan trip land. On unlimited you save A$13 and get a daily reset on top.

Ubigi Japan eSIM prices from Australia

If you're searching for Ubigi Japan prices from Australia, the table above has the 30 day plans in Aussie dollars. For reference, ZenSim's 30 day Japan plans are 10GB for A$26 ($17 USD), 20GB for A$35 ($24 USD), 40GB for A$67 ($43 USD) and unlimited for A$99 ($66 USD), with shorter 5 and 15 day options too. You can see every plan and price at the top of this page.

Not sure which size you need? Light users sticking to maps, transport apps and messaging can get by on 10GB for a couple of weeks. If you're posting daily, using Google Translate's camera mode or watching videos on the train, 20GB to 40GB is the sweet spot, and heavy users or remote workers should go unlimited. Our Japan data guide breaks it down by trip length and travel style.

Buying a Japan eSIM from Australia: Ubigi or ZenSim?

Both brands let you buy online and install your eSIM on your home WiFi before you fly. It sits ready on your phone and switches on once you land at Narita, Haneda or Kansai, so you can order a train ticket or message your hotel before you've picked up your bags.

The differences show up after you hit buy. ZenSim is Australian-owned, prices are in Aussie dollars, and support runs on Aussie time over WhatsApp and Messenger with real humans replying. Ubigi is a global brand based in France, and while its support does the job, it isn't set up around Aussie travellers. If everything installs first time, you may never notice. If it doesn't, a quick WhatsApp to a local team beats a ticket queue in another time zone. And if your phone turns out not to support eSIM, ZenSim's refund policy has you covered.

Ubigi reviews: what to look for

Ubigi's 4.1/5 rating is decent for a global brand, and ZenSim sits at 4.9/5 from 442 reviews on ProductReview.com.au. When you're reading eSIM reviews for Japan, look past the stars and check two things: what people say about speed in busy spots like Shinjuku and Shibuya, and how quickly problems got fixed when something went wrong.

The second one matters more than most people think. Install hiccups usually happen at the worst time, standing in the arrivals hall at 11pm with a train to catch. ZenSim reviewers regularly call out fast, friendly support, which is the difference between a five minute fix and a frustrating first night in Tokyo.

Switching from Ubigi to ZenSim

Already have Ubigi on your phone from a past trip? No dramas. Most eSIM-compatible phones can store several eSIMs, so you can install ZenSim alongside it and choose which one handles mobile data in your settings. There's no need to delete Ubigi unless you want the space back.

Install ZenSim at home before you fly, set it as your data line when you land, and keep your Aussie SIM switched on for texts like bank codes with roaming turned off. Our dual SIM setup guide walks you through it. If you run low mid-trip, you can top up in the ZenSim app without reinstalling anything. Not sure your phone supports eSIM? Run it through our eSIM compatibility checker first.

Other Japan eSIM options

Ubigi isn't the only name you'll come across. For a full rundown of Airalo, Holafly, Saily, Ubigi and more, our best eSIM for Japan guide compares them on price, data and support. If unlimited is what you're after, our best unlimited data eSIMs for Japan goes deeper on fair use limits, and if you're still weighing up options, here's how a pocket WiFi compares to an eSIM in Japan.

Heading to Korea, Taiwan or more of Asia on the same trip? Our Asia travel eSIM covers 15 countries including Japan on one plan. Or if Japan's the only stop, our Japan eSIM page has everything you need.