Japan eSIM: 5 days, 7 days or 10 days — where your money actually goes
Japan is the destination we stock the most tiers for. At 5, 7 and 10 days we list four data tiers each — 1, 2 and 5 GB per day, plus Unlimited — which is twelve prices to choose between. Most people pick the wrong one in the same way: they buy days when what they actually need is data.
The short version: adding days to a Japan eSIM saves you almost nothing per day — 2.5% from 5 days to 10 days. Adding a data tier saves you about 60% per gigabyte. If you have money left in the budget, spend it on gigabytes, not on calendar days.
The full ladder, priced
Japan daily plans, in HKD. The bracket after each price is the total data you get across the whole trip.
| Length | 1 GB/day | 2 GB/day | 5 GB/day | Unlimited |
|---|---|---|---|---|
| 5 days | HK$40 (5 GB) | HK$54 (10 GB) | HK$73 (25 GB) | HK$87 |
| 7 days | HK$55 (7 GB) | HK$75 (14 GB) | HK$101 (35 GB) | HK$121 |
| 10 days | HK$78 (10 GB) | HK$106 (20 GB) | HK$143 (50 GB) | HK$171 |
| Per day, 1 GB/day | HK$8.00 | HK$7.86 | HK$7.80 | — |
That last row is the argument. Day five of a five-day plan costs HK$8.00. Day ten of a ten-day plan costs HK$7.80. Ten days is 2.5% cheaper per day than five — that is not a volume discount, that is rounding. For comparison, 30 days at 1 GB/day is HK$202, or HK$6.73 a day: it takes a full month to earn a discount you would actually notice.
What one extra day costs you
| Tier | 5 → 7 days | 7 → 10 days | Cost per extra day |
|---|---|---|---|
| 1 GB/day | +HK$15 | +HK$23 | HK$7.50 – HK$7.67 |
| 2 GB/day | +HK$21 | +HK$31 | HK$10.33 – HK$10.50 |
| 5 GB/day | +HK$28 | +HK$42 | HK$14.00 |
| Unlimited | +HK$34 | +HK$50 | HK$16.67 – HK$17.00 |
Every extra day is priced at, or just under, the rate you were already paying per day. Days do not get cheaper in bulk. So there is no defensive reason to buy a longer plan: a 10-day plan bought for a 7-day trip is three days and three gigabytes you will not use, at full price.
What one extra gigabyte costs you
This is where the ladder actually bends.
| Upgrade | 5 days | 7 days | 10 days |
|---|---|---|---|
| 1 → 2 GB/day (per new GB) | HK$2.80 | HK$2.86 | HK$2.80 |
| 2 → 5 GB/day (per new GB) | HK$1.27 | HK$1.24 | HK$1.23 |
| 5 GB/day → Unlimited (per day) | HK$2.80 | HK$2.86 | HK$2.80 |
The second gigabyte of each day costs HK$2.80. The third, fourth and fifth cost about HK$1.25 each — less than half. On a 7-day trip, moving from 7 GB to 14 GB costs HK$20 (HK$2.86 a gigabyte). Moving from 14 GB to 35 GB costs HK$26 for twenty-one more gigabytes — HK$1.24 each.
Which means the expensive mistake in Japan is not over-buying data. It is under-buying it. If your usage is somewhere between "probably fine" and "not sure", the top tier is the cheap place to be wrong.
The HK$5 comparison
Here is the mistake in one line.
A 10-day plan at 1 GB/day costs HK$78 and gives you 10 GB.
A 5-day plan at 5 GB/day costs HK$73 and gives you 25 GB.
If your trip is five days long, the second one is HK$5 cheaper and carries two and a half times the data. The first one is what you buy when you are worried about the length of the trip rather than the length of your stay.
The same shape appears at seven days: HK$75 buys 14 GB across 7 days, while HK$78 buys 10 GB across 10. You paid HK$3 more for four fewer gigabytes.
If your whole trip needs less than 5 GB
We also sell a Total Plan for Japan: one data bucket for the entire validity period, no daily reset, and the connection is cut off when it runs out rather than slowed down.
| Plan | Price | Per GB |
|---|---|---|
| 7 days, 1 GB total | HK$12 | HK$12.00 |
| 7 days, 2 GB total | HK$20 | HK$10.00 |
| 30 days, 5 GB total | HK$43 | HK$8.60 |
| 30 days, 10 GB total | HK$82 | HK$8.20 |
| 30 days, 15 GB total | HK$113 | HK$7.53 |
| 30 days, 20 GB total | HK$144 | HK$7.20 |
| 30 days, 30 GB total | HK$199 | HK$6.63 |
| 30 days, 50 GB total | HK$316 | HK$6.32 |
A short, light trip is cheaper on a Total Plan. Seven days at 1 GB/day costs HK$55 and gives you 7 GB. If your whole week needs only 5 GB — easy with hotel WiFi at night — the 30-day Total Plan at HK$43 covers the entire trip and costs HK$12 less. The validity period is longer than you need, and that costs you nothing: you are never charged for days you do not use.
Past roughly 30 GB, the daily plans take over. Thirty days at 2 GB/day is HK$270 for 60 GB — HK$4.50 a gigabyte, well below the best rate the Total Plan reaches. Buy Total when your usage is small or unevenly spread; buy daily when it is large.
The trade-off is what happens when you run out, which we explain in daily vs fixed-data plans: a daily plan drops to 256 kbps and keeps working, a Total Plan stops.
The Korea question
Our Japan & Korea plan and our Japan-only plan are the same price at every tier and every length from 3 to 10 days.
| Length | 1 GB/day | 2 GB/day | 5 GB/day | Unlimited |
|---|---|---|---|---|
| 1 day | HK$11 | HK$13 | HK$17 | HK$20 |
| 3 days | HK$25 | HK$34 | HK$45 | HK$54 |
| 5 days | HK$40 | HK$54 | HK$73 | HK$87 |
| 7 days | HK$55 | HK$75 | HK$101 | HK$121 |
| 10 days | HK$78 | HK$106 | HK$143 | HK$171 |
Those are the same numbers as the Japan-only table above, tier for tier. On the two-country plan, the Korean network costs nothing extra. It also starts at one day rather than three, which covers a layover in Seoul. The only place the two diverge is 15 days, where Korea adds HK$4 to HK$28 depending on the tier.
So if your itinerary might include a stop in Korea and might not, buying the two-country plan removes the decision without changing the price.
What "days" means when you land
- The plan activates automatically on first connection to a mobile network, and must be activated within 30 days of purchase.
- The calendar day is counted in Hong Kong time (UTC+8), not your local clock. In Japan, that means your daily allowance resets at 01:00 local time — the friendliest reset in our whole catalogue. Compare it with the US east coast, where the reset lands at noon and your first day is half gone before you have cleared the airport.
- The practical shape: your first day is partial (it runs from activation to 01:00 the next morning), and your final day runs through to 01:00 after your last night. A 5-day plan activated at 10:00 on arrival gives you roughly 15 hours on day one plus four full days.
That is the point worth repeating before you decide between 5 and 7 days: on a Japan plan, the days you buy are close to real days on the ground. There is no timezone tax to pad for — which is one more reason not to inflate the length. The rest of the setup basics — activation, identity verification, APN — are in the FAQ.
Choosing in one line
| If your trip is… | Buy |
|---|---|
| 3–5 days, city travel, hotel WiFi in the evening | 5 days, 2 GB/day — HK$54 |
| 5–7 days, maps + social + photos, no video | 7 days, 2 GB/day — HK$75 |
| 5 days with video calls or laptop tethering | 5 days, 5 GB/day — HK$73 |
| 7–10 days, working or streaming daily | 10 days, 5 GB/day or Unlimited — HK$143 / HK$171 |
| Any length, under 2 GB total (light use, WiFi-first) | 7 days, 2 GB Total Plan — HK$20 |
| 7 days, 3–5 GB total | 30 days, 5 GB Total Plan — HK$43 |
| Japan plus a stop in Korea | Japan & Korea plan — same price as Japan alone |
Quick answers
Is a 10-day plan cheaper per day than a 5-day plan?
Yes, by 2.5% at the same tier — HK$7.80 against HK$8.00 per day. That is not a reason to buy a longer plan.
Should I buy 10 days for a 7-day trip in case my flight is delayed?
No. The extra HK$23 buys three days you will not use and three gigabytes you will not use. For HK$20 you can instead move from 7 GB to 14 GB on the 7-day plan, and the plan is still running on the days you are actually there.
What happens to data I do not use?
On a daily plan, each day's unused allowance expires that night and does not carry over. On a Total Plan there is no daily allowance to lose — the bucket lasts until it is empty.
Is the Unlimited tier worth it?
It costs HK$2.80–2.86 more per day than 5 GB/day — HK$20 across a 7-day trip. If video calls are on your schedule, or you would rather stop estimating, that is the cheapest insurance in the table.
Which networks does the Japan eSIM use?
KDDI and SoftBank, on 4G and 5G, with free switching between the two so the phone can move to the stronger signal.
Plans for the trip you are actually taking.
Daily and total-data eSIMs for 16 destinations across Asia, the Middle East and North America — from HK$9 for a day, QR code by email, full refund any time before we send it.
Browse all plans: https://esim.uhuibao.com/collections/all