Japan is having a serious moment with Irish tourists right now. The weak yen has made one of the world's most expensive destinations suddenly feel like decent value, and flights from Dublin — though still a connection job — are more accessible than ever. Whether you're heading over for cherry blossom season (March to May) or the fiery autumn foliage in October and November, one thing is certain: you are going to want data, and you're going to want it working the second you land.
Japan's mobile network is genuinely world-class. NTT Docomo, SoftBank, and au between them blanket the country in excellent 4G LTE and rapidly expanding 5G. You'll have signal on bullet trains, in mountain villages, and in the deepest basement ramen spots in Shinjuku. This is not a country where you'll be rationing your data out of fear of dead zones. The infrastructure is there — you just need to make sure you can tap into it properly.
Pocket Wi-Fi vs eSIM: Why Bother With a Device?
For years, the standard advice for Japan was to rent a pocket Wi-Fi unit at the airport. They work fine, but they're a bit of a faff in practice. You're carrying an extra device, charging an extra battery, and if you're travelling solo you can't wander more than a few metres from your bag without losing your connection. There's also the return — you have to post the thing back before you leave, which is fine until you're scrambling for a post box at Narita at 6am.
An eSIM sidesteps all of that. You install it on your phone before you leave Ireland, it activates automatically when you land in Japan, and you never have to think about it again. No hardware, no rental desk queue, no return logistics. Your phone number stays the same for calls and texts, and your Japanese data just runs quietly in the background.
💡 Check your phone is eSIM-compatible before you travel — most iPhones from the XS onwards and the majority of modern Android flagships support it. If you're unsure, go to Settings and search for "eSIM" or "Add Mobile Plan."
For Japan specifically, look for a plan offering at least 10–15GB for a two-week trip. Data usage creeps up fast when Google Maps is doing the heavy lifting across Tokyo, Kyoto, Osaka, and everywhere in between. Some plans offer unlimited data with speed throttling after a threshold — that can work fine for navigation and messaging, but if you're uploading videos or doing video calls regularly, a higher-data unthrottled plan is worth the few extra euro.
Getting Out of the Airport Without Losing the Plot
This is where having data sorted in advance really earns its keep. Both Narita and Haneda serve Tokyo, and neither is a simple hop into the city.
Haneda is the closer of the two — the Tokyo Monorail or Keikyu Line gets you into central Tokyo in 30–40 minutes. Narita is a much longer haul: the Narita Express (N'EX) takes around 60–90 minutes to Shinjuku or Tokyo Station and costs roughly ¥3,000 (about €18–19 at current exchange rates). The Keisei Skyliner is slightly cheaper and drops you at Ueno and Nippori.
Here's how to handle the journey without panicking at the ticket machine:
- Install your eSIM before you leave Ireland and test that it's set up correctly on your home network.
- Land in Japan, clear immigration, and your eSIM data should kick in automatically — open Google Maps to confirm you have signal.
- Download the Hyperdia or Google Maps app in advance for train routing, but having live data means you can re-route in real time if needed.
- Get a Suica or Pasmo IC card from the airport — these rechargeable cards work on almost every train, subway, and bus in Japan and save you queuing for tickets every single time.
- Screenshot or save your accommodation address in Japanese characters before you leave home — taxi drivers and some locals may not read Roman script easily.
Japan's train system looks intimidating on a map but is actually very logical once you're in it. The colour-coded lines, bilingual signage, and near-perfect punctuality make it manageable — but only if you're not also battling a dead phone or a borrowed Wi-Fi hotspot that someone else in your group has wandered off with.
The bottom line is simple: Japan rewards prepared travellers. Get your eSIM sorted before you fly, pick a plan with enough data for a proper two-week trip, and you can focus on the things that actually matter — the food, the temples, the vending machines that somehow have everything you need at 2am.
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