The True Cost of au Kaigai Hodai in Europe (2026) vs. Lotsotravel eSIM

Fourteen days through Italy and France on au海外放題 costs ¥14,000 if you reserved it and ¥16,800 if you didn't. Kaigai Hodai is the 24-hour unlimited data pass that au, the mobile brand of Japanese carrier KDDI, sells for use abroad. The same fortnight on a Lotsotravel Europe eSIM is $8.95 in US dollars, roughly ¥1,400. The rest of this post is the arithmetic.

au advertises Kaigai Hodai as "800円／日〜", from ¥800 a day. Europe never gets that price. The ¥800 rate is limited to a list of 17 destinations, all of them in the Americas, Asia or the Pacific. Everywhere else au serves, Europe included, sits one band up: ¥1,000 per 24 hours if you reserve in advance, ¥1,200 if you don't. A Japanese traveller who budgets from au's homepage gets a bill 25 to 50 percent above the advertised number.

The two price tags, side by side

Why Europe is never the ¥800 price

au's rate card spells this out. The ¥800 rate is tagged 「予約割」17の国・地域限定: the reservation discount, in 17 destinations only. The page sums those up as 韓国、アメリカなど, Korea, the US and the like. The ¥1,000 rate is tagged サービス提供対象の国・地域すべて, every destination the service covers.

UQ mobile, another KDDI brand, announced the same service and named 16 entries, the same names au's table lists today. au counts them as 17 destinations. Every one sits in the Americas, Asia or the Pacific: Korea, Taiwan, Hong Kong, Macau, Thailand, the Philippines, Vietnam, Singapore, Malaysia, Indonesia, Cambodia, Laos, Hawaii, the US mainland, Canada and Puerto Rico. au can change the list without notice. No European country has ever been on it, which is why France, Italy, Spain, Germany and the UK all price at ¥1,000. Skip the reservation and you pay a flat ¥1,200 per 24 hours, wherever you are.

Three details from au's charges page and multi-country FAQ set what a European itinerary costs.

One ¥1,000 country prices the whole window. Travel Seoul then Paris inside one 24-hour period and you pay ¥1,000, not ¥800. au's rule is that if even one destination in the itinerary is a ¥1,000 destination, the rate is ¥1,000 per 24 hours.

The reservation is worth ¥200 a day and nothing more. It buys no extra data and no better coverage, only the ¥1,000 rate instead of ¥1,200. Over a two-week trip that's ¥2,800, about $18, for remembering to open an app before you fly.

And "unlimited" has a ceiling. au's service page says only that speeds may be restricted after a large volume of data in 24 hours. KDDI's 15 October 2026 renewal release puts numbers on it: past 10GB in 24 hours, speed is limited to 5 Mbps at most. For a week of hotspotting that is a workable ceiling, not a cliff.

The clock au gets right

Kaigai Hodai's 24-hour window is better designed than its closest Japanese rival's. It runs 24 hours from the start time you reserved. If you didn't reserve, it runs from the moment you tap 利用開始 ("start using") in the app or on the SMS link au sends when you land. And if your flight slips, au's FAQ says the time you start using it becomes the start time. A delayed arrival doesn't eat a paid day you never used.

Rival carrier NTT Docomo's Sekai Giga Shihodai bills differently, against 0:00 to 23:59 Japan Standard Time (JST) wherever you are. JST midnight falls in the late afternoon in Paris or Rome. A Docomo customer who checks a map at 3pm and again at 6pm can cross a billing boundary in between and pay twice. au doesn't do that, and its daily rate is lower too. What au doesn't fix is the shape of the product. You're still renting data by the day, at a rate that doesn't fall as the trip gets longer.

What five real trips cost on each side

These are five European itineraries we see often in orders from Japanese customers. Lotsotravel figures are live VIP prices, the price you pay through a link on this blog, on the Europe regional plan, which covers 33 countries on one eSIM. au figures assume you pay the daily rate, so you aren't on one of the premium plans covered further down.

Against the reserved rate, the eSIM is 84 to 90 percent cheaper on all five trips. The gap widens with trip length because Kaigai Hodai has no ceiling of its own. There's no 20-day cap and no weekly rate, nothing that makes day 18 cost less than day one. Our 10GB plan costs the same $8.95 whether you spread it over 10, 15 or 30 days, so stretching a trip on the same data costs nothing extra.

Who the ¥18,000 benefit covers

On au's premium tariffs, part of the Kaigai Hodai bill comes bundled with the plan. KDDI's auバリューリンクプラン release (the au Value Link Plan) says au takes up to ¥18,000 a month off Kaigai Hodai charges. At the ¥1,200 walk-up rate, KDDI describes that as 15 days free. The eligible plans are auバリューリンクプラン, 使い放題MAX＋ and 使い放題MAX, the auマネ活プラン family and the データMAXプラン family.

Four limits come with it.

The plan is the expensive part. auバリューリンクプラン lists at ¥8,008 per month including tax. It only falls to ¥5,478 once you stack three discounts: the three-line family discount, au smart value and the au PAY card payment discount. The roaming benefit comes with au's top consumer tariff, not a cheap one.

The allowance resets each month. au's support FAQ says unused Kaigai Hodai benefit does not carry over to the following month. Two one-week trips in the same calendar month share one ¥18,000 allowance. Split the same trips across a month boundary and each gets its own.

Day 16 costs money again. The cap is a yen figure. On a 21-day trip inside one month it covers about 15 days at the walk-up rate, or 18 at the reserved rate. After that au bills normally, which is why the 21-day row in the table above costs even a premium-plan customer.

The benefit belongs to the eligible line, not the household. A partner on a cheaper au plan, a UQ mobile line or a child's handset pays the daily rate. One eSIM shared by tethering, or a cheap eSIM per phone, covers them.

Off those plans, the daily rate is the price, and the table above is the comparison.

Dual-SIM workflow for au customers in Europe

Most recent phones can run two lines at once. This setup keeps your au line for your Japanese number and puts your data on the eSIM.

Step 1. Buy the Europe eSIM 3 to 7 days before you fly

Light use (maps, LINE messages, the odd photo upload) takes roughly 3 to 5GB a week. Video calls, a tethered laptop or posting video take more, so budget 1 to 2GB a day. We email you when your QR code is ready, and you open it on the website.

Step 2. Install the eSIM at home, on Japanese Wi-Fi

On iPhone: Settings → Cellular → Add eSIM → scan the QR code. On Android: Settings → Network & internet → SIMs → Add eSIM. Label the line "Travel" so you can't confuse it with your au line. Installing before departure means you land connected instead of hunting for airport Wi-Fi.

Step 3. Turn off data roaming on the au line, before you board

Settings → Cellular → tap the au line → Data Roaming OFF. On Android: Settings → Network & internet → SIMs → au → Roaming OFF. Voice and SMS keep working, so your Japanese number still rings and still receives bank and card one-time passcodes. This step is what makes an accidental ¥2,980 海外ダブル定額 day impossible.

Step 4. Configure the default lines

• Cellular Data: Travel (the new eSIM)
• Default Voice Line: au
• iMessage / FaceTime: au
• Allow Cellular Data Switching: OFF. This stops iOS from quietly moving your data back to the au line when the eSIM signal dips in a metro tunnel or a thick-walled building. That fallback is how a "no roaming charges" trip usually ends up with roaming charges.

Step 5. Activate on arrival

Switch cellular data to the Travel line when you land. The eSIM connects to a European partner network in about 30 to 60 seconds. No reservation, no app, no 24-hour clock to watch.

What this comparison leaves out

The arithmetic above isolates the price of data. Three things sit outside it, and any of them could matter more to your trip than the money.

Voice quality is the first. Both options hand you to a European partner network. Call quality then depends on your handset, the audio codec it uses and which partner you land on. We have no representative dataset, so we don't claim one.

Speed under load is the second, and it cuts both ways. Kaigai Hodai caps at 5 Mbps after 10GB in a day, which is far faster than the 128 kbps floor on our unlimited plans once their allowance is spent. Our fixed-data plans have no such floor, because they stop at the allowance. Local networks also sometimes deprioritise roaming traffic at peak times, and neither option promises anything during a stadium concert or a New Year countdown.

The third is your contract. au's bundled benefit, the discounts stacked on auバリューリンクプラン and whatever your household already pays for those lines are all specific to you. We've priced the published rates. Check your own bill against them before you fly.

The buy

au Kaigai Hodai is a better-built daily roaming product than most. The 24-hour window rolls instead of following the clock, a late arrival doesn't cost you a day, tethering is included, and the premium-plan benefit is real. None of that changes the shape of the price. Europe is a ¥1,000-a-day destination, ¥1,200 if you forget to reserve. A day rate that never falls means two weeks in Italy cost about ten times the eSIM that covers the same fortnight across 33 countries.

So for a European trip, install a Lotsotravel Europe eSIM and turn data roaming off on the au line before you board. Your Japanese number stays live for calls and passcodes. Five minutes of setup, and the savings land the moment the plane does.