1. What gets checked, field by field
A Japanese listing buries the decisive facts in a specification table and a free-text remarks box. Each of these is extracted, normalised and graded:
Road classification 道路種別
Whether the access route is a designated Article 42 road, a 42-2 legacy narrow road, a private lane, or nothing legally recognised at all.
Road width and frontage 道路幅員・間口
The width of the road and how many metres of your plot actually touch it. Under 2m of frontage generally means no rebuild.
Setback requirement セットバック
Whether the listing already admits a setback, and how deep it would be from the road centreline.
Private-road burden 私道負担
Land inside your title that is actually roadway, plus wording that says a burden exists or explicitly does not.
Zoning and use district 用途地域・市街化区域
Urbanisation promotion vs control area, and the use district that caps what you may build.
Utilities 上下水道・ガス・電気
Mains water, sewer, gas and electricity — connected, available but needing a paid connection, septic, well, LPG, or simply not disclosed.
Structure, floors and year 構造・階数・築年
Timber, light or heavy steel, reinforced concrete — plus build year against the 1981 earthquake code line.
Registration problems 未登記・増築未登記
Unregistered buildings or extensions and missing completion certificates, which block financing and complicate resale.
Price and ownership costs 売買価格・維持費
The asking price, purchase costs, renovation allowance, utility work and likely annual holding costs.
Location and access 最寄駅・周辺施設
Stations, travel times, shops, schools, medical care and civic services, with names presented in English.
Anything the listing does not state is recorded as not disclosed. A missing fact is never treated as a pass.
2. How the setback maths works
Under Article 42-2 of the Building Standards Act, a plot facing a road narrower than 4 metres must pull its building line back to where the road would be if it were 4 metres wide — measured from the centreline.
The formula
setback depth (m) = (4.0 − road width) ÷ 2 land surrendered (m²) = setback depth × frontage
Worked example
A plot of 120 m² faces a 2.7 m road with 6 m of frontage.
- Setback depth = (4.0 − 2.7) ÷ 2 = 0.65 m
- Land surrendered = 0.65 × 6 = 3.9 m²
- Buildable land left = 120 − 3.9 = 116.1 m²
That strip stays in your title and you keep paying tax on it, but it cannot be built on or fenced. Where only one side must set back — because the opposite side is a river or a cliff — the full 4 m is taken from your side instead, which roughly doubles the loss.
3. How the risk grade is decided
Deal-breaker
The listing says rebuilding is prohibited, frontage is under 2 m, there is no designated road, or the plot sits in an urbanisation control area with no building right.
Conditional
Rebuilding looks possible but something costs you: a setback, a private-road burden, missing utilities, an unregistered extension, or road details the listing never disclosed.
Clear
A designated road of 4 m or more, adequate frontage, no setback wording, no private-road burden, and lifelines connected.
The grade is deterministic: the same listing text always produces the same grade. Language models are used to read and translate the page, not to decide the verdict.
4. Where the data comes from
The primary source is always the listing page you paste. Press Find more sources and the same property is searched for on other Japanese portals and agent sites.
- Candidate pages are matched to your property by locality plus price or land area, so a neighbouring plot is not mistaken for yours.
- Where sources disagree, the value stated by the most sources wins; a tie falls back to the more cautious reading.
- A detail is only added to your report when enough sources back it — a single outlier cannot turn an undisclosed field into a fact.
- Every newly filled detail is listed with the site it came from and a link straight to the card in your report that changed.
Location context is added from Japan's national mapping service. Where available, official zoning, recorded transactions and published land values are added from Japan's government property-data service.
5. What's in the report
Verdict banner
One sentence answering can this be rebuilt, plus the identity facts.
What this house really costs
Price, agency fee, taxes, utilities and renovation — plus the yearly cost of owning it.
Is the asking price fair?
Asking price per square metre compared with nearby recorded prices or official land values.
Location health
A conservative read of access, services and signs that the area may be stable or shrinking.
Renovation condition tier
An A–D condition band with a renovation cost range and the listing signals behind it.
Deal-breakers first
Everything that could kill the purchase, ranked.
Location and commute
English station and line names, travel times, and nearby shops, schools, medical and civic facilities.
Negotiation leverage
Evidence-backed talking points and a defensible opening-offer range.
Road and setback
Classification, width, frontage, setback depth and land surrendered.
Infrastructure audit
Water, sewer, gas and electricity status with connection costs.
Closing-cost breakdown
Taxes, registration, legal fees, agency fees and other likely purchase costs.
Renovation and demolition flags
Structure, age, earthquake code, permitted works and demolition cost range.
Possible subsidies
National and local schemes that may help with renovation, seismic work or relocation.
Official records and hazards
National map context, available zoning and price records, plus hazard and title warnings.
Foreign-buyer guidance
Ownership, finance and remote-closing points that commonly affect overseas buyers.
Source trail
Every matching page, disagreement and newly filled detail, linked back to the report section it changed.
Full-report action tools
Publisher and City Hall enquiry scripts, a printable field checklist, sharing and PDF export.
6. Unlock, save and share
The first result gives you the headline verdict and selected findings. Unlocking a report reveals the detailed calculations, cost ranges, source evidence, enquiry scripts and printable inspection checklist.
- Without an account you can run 3 free checks per day. A free account removes the daily limit.
- Signed-in users can save reports and re-run them when a listing changes.
- Unlocked reports can be shared through a revocable read-only link.
- The PDF contains the due-diligence findings for an agent or adviser; interactive scripts and the field checklist stay in the web report.
7. Limits, stated plainly
This is a screening tool
- The report can only be as complete as the listing. Japanese listings routinely omit road width and utility status.
- The final authority is the municipality's Building Guidance Division. Confirm before you sign anything.
- Government zoning, transaction and land-price records depend on address accuracy and local coverage. When unavailable, the report says so instead of treating the listing wording as an official confirmation.
- Costs are estimates based on standard Japanese rates, not quotations.
- AkiyaCheck is not a licensed broker, land surveyor or administrative attorney.
8. Frequently asked questions
Do I need to read Japanese to use it?
No. Paste the Japanese listing URL and the findings, station names, railway lines and nearby places are presented in English. Important Japanese legal terms remain available in the report so you can quote them accurately.
Is this legal advice?
No. AkiyaCheck is a screening tool. The authority on whether a plot can be rebuilt is the municipality's Building Guidance Division (建築指導課). The report gives you a Japanese enquiry script so you can confirm quickly.
What if the listing does not state the road width?
Undisclosed is reported as undisclosed — never as a pass. The report flags it as unverified and adds the missing item to your enquiry questions.
Why does the report sometimes change after 'Find more sources'?
Other sites often publish details the original listing omits. When several sources agree on a fact, that agreed value is used and the sources backing it are listed.
What is included in an unlocked report?
An unlocked report includes the detailed calculations, price and renovation ranges, source evidence, Japanese enquiry scripts, printable inspection checklist, sharing and PDF export. The public sample is a shorter preview and does not include every action tool.
Ready to check a listing?
Paste the property URL and get the rebuild verdict, true cost, price context and location risks in about a minute.
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