The methodology and the money, on one page
How we test, and what we earn
A comparison site that hides its incentives is an advertisement. Here is exactly where the numbers come from, what we have not done, and who pays us what.
What we earn, brand by brand
the actual rates
| Brand | We earn | Where it appears on this site |
|---|---|---|
| GigSky | 20% | The default pick, because it lists NTT Docomo on every Japan plan and is the cheapest 10GB of the brands we link. It is also our highest rate, so read the reasoning and decide for yourself. |
| Yesim | 18% | Cheapest 5GB with a month's validity and the only 30GB plan for Japan. Flagged every time with its Trustpilot suspension history. |
| Saily | 15% | The unlimited and hotspot pick, for the largest published daily cap in Japan and the best support record on the site. |
| Airalo | 12% | The corridor pick and the cheapest 20GB. Our lowest rate and still the recommendation for most first trips that stay in the cities. |
| Drimsim | fixed fee | One page only, the phone number page, where we say plainly that it is the weakest of the three options for that problem. |
| Ubigi | nothing | Reviewed in full on its own page and listed in every comparison table. Lists KDDI, NTT Docomo and SoftBank, and is cheaper than anything we link at 10GB. |
| Nomad | nothing | Listed in the comparison tables because its prices are real and sometimes the lowest. |
| Mobal | nothing | Named as the practical route to a Japanese phone number, and listed as a local KDDI unlimited option, unlinked. |
| Sim Local | nothing | Listed for its KDDI (au) unlimited plan, the only 7-day Japan plan we found sold with no daily cap. |
| Pocket wifi renters | nothing | We wrote a page saying when to rent a router instead, which costs us the sale. |
All commissions come through the Travelpayouts network. The rate never changes your price, and it has never changed the order of a recommendation. The test we apply: strip the commission out and does the reasoning still hold. If the answer is no, the recommendation changes.
Where do the prices come from?
each brand's own page, with a date
Plan prices come from each provider's own Japan page, in USD, before any promotional code, and were last re-checked in 2026. Where a page renders prices with JavaScript we read the same plan data the page loads: GigSky's public plan feed, Airalo's page data with the USD currency selected, Nomad's USD price field. Mobal sells in yen only, so we show yen and say when we convert.
What we could not check automatically, we say: Saily's page refuses our automated reader, so we read it by hand in a browser. Every Saily plan, its 5GB daily cap, the 1 Mbps after it, its midnight reset and its networks are current. Trustpilot scores were re-read on trustpilot.com in 2026.
Every table carries the year it was checked. Prices in this category move by a dollar or two a month, and sometimes a brand restructures: GigSky now sells its 3.5GB-a-day Japan plan as Unlimited for 1 to 30 days, and Ubigi now prints its fair-use numbers. If a number on your screen does not match ours, trust the provider's checkout.
Network claims: published, or we say "not published"
no guessing
This is the rule the whole site is built on. Every claim about which Japanese carrier a provider rides comes from that provider's own Japan page or plan data, on the date shown. Where a provider publishes nothing, the tables say not published.
We do not repeat network claims from blogs, from database entries or from other comparison sites, because those propagate. Saily was the clear case: third-party listings said KDDI, and every table on this site said "not published" until Saily's own Japan page named KDDI and SoftBank, which is what the tables now say. Nomad was the opposite case: we used to write "not published", and its page now lists KDDI au and SoftBank, so the tables say that. That is less satisfying than an answer and it is the truthful thing to write.
Traveler reports are labelled as traveler reports. The Hong Kong exit-address observation on Saily's Japan traffic appears in three places on this site and is described as a reviewer report every time, because that is what it is.
What we have not done
said plainly
What we do check: live prices on each provider's own page, the network each provider publishes for Japan, the fair-use text behind every "unlimited" plan, Trustpilot profiles, and primary sources for legal claims. For the SIM ID law that means the Japanese ministry's own pages and the law text on e-Gov, which is how we found and corrected our earlier, wrong "April 2026" date: the amended law was promulgated on 29 May 2026 and MIC says the new rules apply from April 2027. Pocket wifi is priced from the renters' own rate cards rather than their headline rates.
Those are different kinds of work and we are not going to blur them. A price we pulled is a fact. A coverage note is a well-sourced judgement. A speed test we did not run is not evidence at all, and it will not appear on this site dressed up as one.
The five rules
the ones that cost us money
- Unmonetised providers appear in every table. Ubigi lists all three major Japanese networks and is cheaper than anything we sell at 10GB. It is in every comparison on this site with the reason next to it.
- One real drawback per recommendation. Every pick card on this site names a genuine reason not to buy it. If we cannot find one, we have not looked hard enough.
- Fair-use caps are published or marked missing. "Unlimited" is a daily allowance in Japan, and where a brand will not give the number, the table says so rather than leaving the cell empty.
- Every price carries a date. No exceptions, including in the FAQ answers.
- We say when the answer is not to buy anything from us. Rent a router if there are three of you. Buy Sim Local's KDDI plan if you want unlimited with no daily cap. Get a Mobal SIM if you need a phone number. Those pages exist and they cost us the sale.
Corrections
and what happens to them
If a price here is stale, a network claim is wrong, or your experience on a Japanese network contradicts our coverage table, we want to hear it. The coverage notes in particular rest on published maps and traveler reports rather than on our own measurement, and a specific report from a specific place is worth more than another map.
Verified corrections ship in the next update and we note what changed. Send them here.
Sources & freshness: Commission rates are the current Travelpayouts programme rates for this account, checked 2026, and are published here rather than described vaguely. Plan data: GigSky, Airalo, Yesim, Ubigi, Nomad, Sim Local and Mobal re-checked on their own pages 2026; Saily and GigSky read by hand on their own pages 2026, including GigSky's 3.5GB daily cap (GigSky does not publish the speed after it); Trustpilot checked 2026. About this site · Contact.