A figure about Japan often reaches you several steps removed from where it started: an English article summarizing a Japanese news report, which summarized a ministry release, which was based on a survey table. Each step can drop a condition, change a unit, or blur the date.
This guide explains which Japanese sources usually count as primary for business and market research, what they can and cannot tell you, and how to trace information back to them.
What “primary source” means here
“Primary source” is used differently in history, journalism, law and academic research. In this guide it means the original publication of a piece of information by the party that produced it or is responsible for it — for example, a company’s own announcement, or a ministry’s statistical table.
Two cautions apply:
- Primary does not mean correct. A company’s description of itself is primary for what the company says, not proof that it is true. Official statistics have definitions, sampling limits and revisions.
- Secondary does not mean unreliable. Good reporting and analysis add context the original does not provide. The point is to know which one you are looking at.
Common primary sources in Japan
| Type | Examples | What to check |
|---|---|---|
| Company announcements | Official website, press releases, product and pricing pages | What the company itself states. Claims about itself remain claims. |
| Securities filings and disclosures | Annual Securities Reports on EDINET; timely disclosures on TDnet | Filed information for companies subject to disclosure rules. Check the period covered. |
| Government statistics | Survey results on e-Stat and ministry websites | Survey scope, definitions, and whether figures are preliminary or final. |
| Laws and official documents | Law texts via e-Gov; ministry notices and guidelines | Whether the text is current, and when amendments take effect. |
| Local government publications | Prefectural and municipal websites | Rules and programs can differ by municipality. |
| Industry association data | Statistics and surveys published by the association | Whether figures cover the whole industry or members only. |
Laws in English. The Ministry of Justice publishes English translations of many Japanese laws in the Japanese Law Translation database. The site states that these translations are not official texts and that only the original Japanese texts have legal effect. Use them to understand a law, and the Japanese text to confirm what it says.
Secondary sources and what they are good for
| Type | How to treat it |
|---|---|
| News reports | Usually report on announcements or data from others. When a journalist has obtained information through their own reporting, the article itself may be the original source. |
| Trade and industry media | Useful context and analysis. Check which statements are sourced and which are the writer’s view. |
| Market research summaries | Often summarize a paid report. The definition and method are in the full report. |
| Aggregator and comparison sites | Collect information from elsewhere; may be out of date. |
| English-language summaries | May compress or reinterpret Japanese originals. |
| AI-generated answers | Not a source in themselves. Check any cited page, and the original behind it. |
Secondary sources are often the fastest way to find out that something exists. The problem arises only when a secondary summary is used as if it were the original.
How to trace information back to the original
English article or summary
↓
Japanese news report or blog post
↓
Press release or published report
↓
Original table, filing or document
- Isolate the claim. Separate the specific figure or statement you need from the surrounding text.
- Look for the citation. Japanese documents mark sources with labels such as 出典, 出所, 資料 or 注, usually below a table or chart.
- Search for the document by its Japanese title on the publisher’s website, rather than relying on the link in the secondary source, which may be broken or point to an older version.
- Find the figure in the original and confirm the number, unit, period and definition match what was quoted.
- Check whether a newer version exists, such as revised statistics or an updated report.
If the original is hard to locate, the search techniques in How to Find Information on Japanese Websites — exact Japanese titles, site: and filetype:pdf — are usually the next step.
What to check in the original
Who produced it
Identify the organization responsible, not just the website hosting the file. A report on a ministry website may have been commissioned from a private firm; an association’s figures may be estimates by its secretariat.
When it was published, and what period it covers
The publication date and the data period are different things. A report published in 2026 may contain data for fiscal 2024. Japanese documents also use fiscal years (年度) and era years, which need converting before comparison.
Scope, definitions and notes
Table notes often limit what a figure means: establishments above a certain size, members only, a particular region, a changed definition from a certain year. These notes are usually in Japanese and easy to skip in translation.
Claims and their conditions
Japanese marketing pages often attach conditions to claims using the ※ mark, with the detail in smaller text elsewhere on the page. A claim such as “No. 1 in its category” may apply only to a particular survey, period or definition. Record the condition together with the claim, and attribute it to the company.
Language versions
Where a document exists in both Japanese and English, the English version may be a summary, published later, or less detailed. Some organizations state that the Japanese version prevails in case of discrepancy. When the two differ, note which version you used.
When you cannot find the original
Sometimes the trail ends: the citation is missing, the link is dead, or the document was never published online. In that case:
- Record the furthest source you reached and the steps you took.
- State that the original could not be confirmed.
- Treat the information as unverified in any conclusion that depends on it.
Do not upgrade a secondary figure to “official” because it appears in many places. Repetition often means many sites copied the same summary.
Record the source, not just the link
For each important piece of information, keep:
- The claim or figure, exactly as stated in the original
- Title of the original document or page
- Publisher (the organization responsible for it)
- Publication or update date
- Period the data covers
- Scope and conditions (definitions, units, notes)
- URL, and the date you checked it
- The secondary source where you first saw it, if different
For applying this to market size figures, statistics and industry data specifically, see How to Research the Japanese Market Using Japanese Sources.
If you need Japanese sources traced and checked
Tracing a claim to its origin is simple in principle. In practice it can mean following several links, searching Japanese document titles, reading footnotes and table notes in Japanese, and comparing versions — for every figure that matters.
optimal plan SEARCH’s Japan Research Service researches Japanese-language websites and public sources on your behalf, verifies the findings, and delivers them as an English report with source links wherever possible. Anything we could not confirm is reported as not confirmed, rather than filled in with guesses.
You can describe your question in English. You don’t need to know the Japanese search terms or where to look.
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