Methodology and How to Use

• Holdings (end of month) and flows (during month) are official values exactly as published in the Bank's “Monetary Base and the BOJ's Transactions” table (MD09), in units of ¥100 million. Pages display ¥ trillion, an exact division by 10,000 — no rounding happens before display.
• Change from peak: value[latest] − max(value[m]) over all published months; the percent version divides by that maximum. The peak month is named wherever the figure appears. 12-month pace: mean(value[t−11] … value[t]) over the trailing twelve published flows. A negative net flow is balance-sheet runoff.
• Flows can be genuinely negative (redemptions carry a minus sign), so no percentage rates are computed on a flow series — a percent change across a sign change is arithmetic noise, and the API refuses it rather than serving it.
• Gross outright purchases, redemptions and “other transactions” do not sum exactly to the net JGB flow in every month: some components, such as repo sales to the government, have no live flow series. No surface presents those three as a complete decomposition.

• Every figure is the FSA's own, from table 1 of its half-yearly 金融再生法開示債権 release: claims and total credit in ¥100mn (the FSA rounds each line to the nearest ¥1bn), the bad-loan ratio in percent, the disposal loss and real net business profit in ¥tn. Units differ by line and nothing is rescaled.
• No single release covers the whole history — each carries about twenty half-years — so the dataset stitches table 1 of every release since 2006 and, where two overlap, the newer release wins. That is how the FSA's own restatements are carried; the vintage store keeps what each ingest changed.
• The disposal loss and real net business profit are the full fiscal year at March and the first half at September (the FSA's note 9). They are stored as two series each, .fy and .h1, and are never drawn as one line.
• A half-year is dated to the first day of its closing month (3月期 → 1 March, 9月期 → 1 September), so the twelve-month comparison lines March up with March.

• The FSA's two long-run workbooks behind its results summary: major banks from March 2008 and regional banks from March 2005. Income-statement lines in ¥100mn, loans and bad loans in ¥tn, as published. Ratios the FSA stores as fractions are multiplied by 100, exactly.
• The 3月期 sheet is the full fiscal year and the 9月期 sheet the first half, so every income-statement line is two series (.fy, .h1). Stocks and ratios are one series.
• The major-bank income statement is consolidated (the FSA's （連結） lines) and the regional-bank one is not; the majors' 業務純益 and the regionals' 実質業務純益 are different measures and carry different codes. Capital ratios split at March 2013 into the international and domestic standards; the pre-split ratio is its own series.

• Balance sheet and income statement of every JBA member bank, non-consolidated and consolidated, plus the association's aggregates by bank type, in millions of yen exactly as published in 全国銀行財務諸表分析. The share and change columns the association prints are not stored — they are calculations, and where a page shows one it shows the formula.
• Series are {s|c}.{bank}.{line}: the bank is its 金融機関コード (0001 Mizuho, 0005 MUFG Bank, 0009 SMBC) or a group (all, city, regional, regional-2, trust, other); the line is the association's reference code (a015 deposits, d395 loans, e800 ordinary profit, f850 net income). A code survives renamings and mergers, so a merged bank's series runs on under the surviving code from the merger date.
• Each edition is one point in time, so every edition since fiscal 2001 is read and stitched (earlier editions are Excel 5/95 files the platform cannot open). Editions before fiscal 2014 numbered the lines differently and their consolidated sheets carry no codes; those are matched by line name within the section of the statement, and a line with no modern counterpart is dropped and counted in the release's validation record (about a fifth of lines before fiscal 2006, 2–9% to fiscal 2013, under 1% today).
• Income-statement lines are .fy on March points and .h1 on September points; balance-sheet lines are one series. Trust-account (信託財産) tables are not ingested.

• Yields are the Ministry of Finance's daily constant-maturity par yields for 15 tenors (1–10, 15, 20, 25, 30, 40 years), in percent to three decimals, computed by the Ministry from Japan Securities Dealers Association over-the-counter reference prices. They are shown exactly as published — nothing is fitted, interpolated or smoothed. A tenor with no published value on a date is a gap, and the curve line breaks rather than drawing across it.
• Coverage starts 24 September 1974. Longer tenors begin later — 10-year in July 1986, 20-year in December 1986, 15-year in August 1991, 30-year in September 1999, 25-year in March 2004, 40-year in November 2007 — and the 1-, 2- and 3-year series have real mid-series gaps where short tenors were not quoted.
• Spreads: 2s10s[t] = 10Y[t] − 2Y[t] and 10s30s[t] = 30Y[t] − 10Y[t], in percentage points. Changes: value[t] − value[b], where b is the latest business day on or before the same calendar date one month or one year earlier.
• Yields can be genuinely negative — the 1-year traded below zero through the negative-rate era — and no surface treats a negative yield as missing.
• The policy markers on the history chart are Bank of Japan announcement dates (ZIRP, QE, QQE, NIRP, yield curve control and its end, and subsequent policy-rate changes). They are dates only: annotations, not data.

• Monthly counts of foreign visitors, in persons, by market, shown exactly as published. JNTO computes them from Ministry of Justice immigration statistics: foreign nationals entering Japan, less those whose main residence is Japan, plus landings at a port of call, landings in transit and cruise passengers. Crew are excluded; expatriates, their families and students are included.
• Three releases a month, all official. An estimate (推計値) about three weeks after the month, a provisional figure (暫定値) with full market detail two months later, and a definitive one (確定値). The estimate covers only the largest markets and is rounded to the nearest 100, so on estimate months the named markets do not add to the headline and the regional totals are absent; those months are marked on every surface. Measured across three releases of the source workbook, definitive figures are never subsequently revised and the estimate-to-final change is rounding, about 0.006% at the headline.
• Growth: (arrivals[t] / arrivals[t−12 months] − 1) × 100. Month-over-month rates are not shown: the series is strongly seasonal and an unadjusted monthly change is not interpretable. Recovery index: (arrivals[t] / arrivals[same month of 2019]) × 100 — 2019 is the last full year before the border closed, and comparing like months removes the seasonality.
• Share: arrivals[market] / arrivals[Total] × 100 for the same month. The market table therefore shows the latest month with a complete breakdown, not each market's own latest month — a share is only comparable when every row is the same month.
• Contributions: (arrivals[market, t] − arrivals[market, t−12]) / arrivals[Total, t−12] × 100, in percentage points. The residual is growth[Total, t] − Σ contribution[named markets, t], taken from the published headline rather than by summing the markets left out, so the segments sum to the headline exactly even on estimate months. It is always shown, never dropped.
• Year to date sums the published months of the current year against the same months of the prior year. Where a month is still an estimate, JNTO rounds both it and its own cumulative to the nearest 100, so this sum can differ from the press release by a few tens of people. Neither figure is adjusted to match the other.
• Market mix: Σ arrivals[market, t−11 … t] / Σ arrivals[Total, t−11 … t] × 100. Shares are taken over a trailing twelve months so a market's summer peak reads as seasonality rather than a change in the mix. A share is a percent of arrivals, not of spending — markets differ several-fold in what each visitor spends.
• Concentration: HHI[t] = Σ share[part, t]² over the parts that actually partition the total — every leaf market, every residual JNTO publishes, and whatever is left of the headline not itemised in that era, since the residual rows only begin in 2016. Including that remainder is what lets the index mean the same thing in 2003 as today. A higher value means arrivals come from fewer places. The series ends before the headline does: an estimate month does not publish every market, and an incomplete partition is not an index, so those months are gaps.
• The seasonality view groups the same published counts by calendar month, one line per year. 2020–2022 are left out of it: with the border shut those lines sit on the axis and flatten every other year into an unreadable band. They remain in the table, the other charts and every export.
• Where arrivals are shown against the consumer price index for hotel charges, both are indexed to the same month of 2019 so they share one comparable scale; neither is read off the other's units, and the two are published by different agencies on different schedules, so they can end in different months. That chart shows two series moving together. It is not evidence that one causes the other.

• Japan Tourism Agency Accommodation Survey (宿泊旅行統計調査), shown exactly as published. Two measures live here and are never mixed: guest nights are person-nights — one visitor staying three nights is three person-nights and one person, which is why they are never compared with or added to visitor arrivals — and room occupancy is a published percentage. Pages show guest nights in millions (person-nights ÷ 1,000,000); no other transformation is applied.
• These are sample estimates, and the survey says so. Figures are grossed up from a sample of properties, and the Agency publishes its own standard error rate for each prefecture and breakdown — about 1% at the national headline, near 30% for the smallest properties in a thin prefecture. It also marks individual weak cells. A marked value is kept and counted rather than dropped, and the count of marked values is recorded on every release. A room occupancy rate above 100% is rare but real for the same reason — Tottori's city hotels print 104.3% for August 2011 — and is shown as published, never capped.
• The January 2026 break is a change of definition, not of demand. From that survey the Agency stratifies properties by room count instead of employee count, and states that year-on-year comparisons spanning the change may carry its effect. Every surface marks the break with a rule on the chart and a notice whenever a comparison straddles it. Three consequences are structural: property-size series begin at the break, because the pre-2026 employee-count bands measure something else and are deliberately not spliced on; the nationality list widens from 21 categories to 24, so the Nordic region, the Middle East and Mexico begin there; and the residual "Other" is carried as two separate series, because before 2026 it also contained those three. Nothing is adjusted to bridge the break.
• Three releases a month, all official — a first preliminary covering national totals only, a fuller second preliminary about a month later, and annual definitive figures the following year. Unlike visitor arrivals, this survey genuinely revises, so its point-in-time vintages carry real information. A release is assembled from the Agency's trend workbook, its annual definitive workbooks and the monthly second-preliminary files; where two carry the same figure the more settled one is used, and the agreement rate between them is recorded as a check that no column has been misread.
• Growth: (guest nights[t] / guest nights[t−12 months] − 1) × 100. Occupancy is a ratio, so it is differenced, never divided: occupancy[t] − occupancy[t−12 months], in percentage points. An occupancy rate is never averaged across areas — the national figure is the Agency's own, not a mean of the prefectures. Recovery index: guest nights[t] / guest nights[same month of 2019] × 100.
• Shares: foreign guest nights[t] / guest nights[t] × 100, and guest nights[area] / guest nights[All Japan] × 100. The 47 prefectures partition the country; the ten transport-bureau regions republish the same nights and are never added to the prefectures or given a share.
• Contributions: (guest nights[prefecture, t] − guest nights[prefecture, t−12]) / guest nights[All Japan, t−12] × 100, in percentage points. The residual is taken from the published headline rather than by summing the prefectures left out, so the segments sum to the national rate exactly. It is always shown, never dropped.
• Nationality shares use the nationality table's own published total as the denominator. That table covers larger properties only — 20 rooms or more from 2026, 10 or more employees before — so its categories do not sum to the all-properties foreign guest nights and must not be divided by it. Guests whose nationality the survey does not identify are shown as a disclosed residual, normally a few percent of a prefecture's foreign nights and far more in a thin cell, and are never spread across the named categories.
• The purpose split classifies the property, not the guest: "leisure-majority" means at least half of that property's guests stayed for leisure. It is a proxy for the business/leisure mix, not a measurement of it. Neither the purpose split nor the residence split sums to total guest nights — the survey also publishes nights whose purpose or residence is unknown — so they are drawn as separate lines, never stacked into a false whole. The five property-size bands do sum to the total exactly.
• Municipality figures are counted, not grossed up: the Agency publishes them as responses received rather than as an estimate for the whole municipality, so they are not comparable with the prefecture totals. A municipality appears only in months where at least ten of its properties responded, so the list changes month to month; a town absent from a month is missing, never zero. City names are carried in Japanese as published, with the prefecture romanised — the Agency publishes no romanisation and one is not invented here.

• Ministry of Finance customs figures for Japan's trade in semiconductors, semiconductor components and semiconductor manufacturing equipment, by partner country, from January 2001 — from the principal-commodity by country tables (概況品別国別表) of the Trade Statistics of Japan, shown exactly as published. Value is published in thousands of yen; pages show billions (value ÷ 1,000,000), and no other transformation is applied. Quantity is published in the commodity's own unit — pieces for a chip, kilograms for a machine — which is why unit values are never compared between commodities.
• Export and import commodity codes are separate vocabularies and do not correspond. Code 70311000 is semiconductors and electronic components on the import side and audio equipment on the export side. Every surface validates a commodity against the direction being read, and the two directions are never joined on a code.
• A published group is never the sum of the items shown beneath it. The Ministry publishes components inside a group that this dataset does not carry, so Semiconductors & electronic components always exceeds integrated circuits plus discrete semiconductors plus thermionic tubes. Groups and items are drawn together for comparison and must not be added.
• Months the table has not reached are published as zero, and are dropped. The current-year table returns 0 for every month after the last one compiled. Coverage is derived per year as the last month carrying any non-zero value anywhere in the slice, and later months are not stored. Zeros inside the covered window are real — no customs entry was recorded with that partner that month — and are kept.
• World totals: Σ value[partner, commodity, t] over every partner the Ministry publishes for that commodity, including the non-country entries (goods shipped to order, unknown destinations, bonded areas). This table publishes no world row, so the total is summed here and carries no official badge.
• Twelve-month total: Σ value[t−11 … t]. Trade is lumpy and a single large shipment moves a partner's monthly figure several-fold, so shares, unit values and the destination mix are read off this sum rather than one month. The sum is left blank until twelve months of history exist.
• Growth: (value[t] / value[t−12 months] − 1) × 100. Month-over-month rates are not shown: the series is seasonal and lumpy. Share: 12-month total[partner, t] / 12-month total[world, t] × 100, with the destination-mix residual 100 − Σ share[named partners, t], so the bands sum to 100% in every month and no partner is dropped.
• Unit value: (12-month total of value[t] × 1,000) / 12-month total of quantity[t], in yen per unit shipped. This is an average realised price across a year of shipments — not a price index, not quality-adjusted, and not comparable between commodities or against the consumer price index.
• A figure too small to show at the displayed scale reads as <0.1 rather than rounding to 0.0, so a rounded-down value can never be mistaken for a genuine zero or a month with no entry.
• Four release stages, all official — preliminary (速報), confirmed (確報), revised (確々報) and final (確定). The current year moves through all of them, so a recent month will change; a new release is stored whenever the Ministry republishes any year of the table, and the as-of view returns the figures as they stood on any past date.
• Silicon wafers come from the HS-detail tables (品別国別表), dataset trade-inputs, as HS 3818.00 — doped chemical elements in the form of wafers. e-Stat publishes no names for HS lines, so the names are set from the Customs tariff schedule; the export and import schedules split the heading differently (-100/-900 and -010/-020), and the import silicon line was confirmed by its value-per-kilogram signature. The residual "other doped elements" line is kept separate and never added to silicon. On the supply-chain chart the three steps — wafers, integrated circuits, equipment — are indexed to a common base month so lines of very different size can be read together; they are three different products and are never summed.

• Rice contract prices are the volume-weighted average of contracts actually struck between shippers handling 5,000 tonnes a year or more and wholesalers — not a quote and not an auction clear. Yen per 60kg bag of brown rice, first-grade table rice, including freight, packaging and consumption tax, published by MAFF for each 産地品種銘柄 origin-and-variety brand. A brand-month with no contract, or with under 100 tonnes contracted, is not published; the Ministry does not distinguish the two and neither does this site. Both stay gaps.
• The all-brand average is the Ministry's, not ours. It is weighted by the previous crop year's inspected quantity by brand, stored exactly as released, and never recomputed from the brand series shown alongside it — which is why it need not sit at the arithmetic mean of the lines on the chart.
• A regional Koshihikari is one series across a layout change. Until the 2017 crop year MAFF carried the growing area in a separate 地域区分 column; from 2019 it is inside the brand name as コシヒカリ（魚沼）. Both are stored as the same series, so the history does not break in half at 2018.
• The crop-year average price is calculated: mean of the published monthly contract prices for September of year y through August of year y+1 — the marketing year of the crop harvested in year y, which is the year the cost survey prices. A crop year missing any of its twelve months is left out rather than averaged short.
• Three published cost levels, and the difference between them is the point. 費用合計 is what was spent; 生産費（副産物価額差引） nets off straw and other by-products; 全算入生産費 adds imputed interest on the farmer's own capital and imputed rent on the farmer's own land. All three are stored as published. A farm-gate price can sit above the first and below the third, and which one is quoted is usually where an argument about farm policy is being had.
• Rice inventories: the crop-age split does not add to the total, and is not meant to. MAFF itemises the current crop and one-year-old rice; rice two years old and older is inside the stage total with no row of its own. The residual is the difference and is never shown as zero. Shippers and wholesalers do sum to the combined stage, bar the Ministry's independent rounding of each row to whole 10,000 tonnes. Stocks are private trade stocks only — rice on the farm and the government reserve are outside the table.
• The farmer's terms of trade is calculated: (farm output price index[t] ÷ farm input price index[t]) × 100, from published index values on the same base year. Above 100 means output prices have risen further from the base than input prices have. It is not an official statistic and carries no badge.
• Co-operative amounts are thousands of yen as published; pages show billions (value ÷ 1,000,000), an exact conversion. 営農指導事業分配賦額 — the farm-guidance loss charged back to each earning business — is a published line of the Ministry's own statement, not an allocation made here. 共通管理費等 is overhead belonging to no single business: it is part of the group total, so adding the five businesses without it does not reconcile.
• Fiscal and crop years are dated to a fixed month. A co-operative fiscal year runs April to March and is dated to the 1 April it begins (令和5事業年度 → 2023-04-01); a rice crop year in the cost survey is dated to 1 January of its harvest year (令和5年産 → 2023-01-01). Both are conventions of this site, chosen so a year-on-year measure compares like with like.

• Revenue by region, the customers a company names, and its reportable segments come from the segment-information note (セグメント情報等) of the annual securities report on EDINET, for the current and prior fiscal year. The note is a text block, not tagged numbers: every figure is parsed from the filer's own HTML tables, and each filing carries a status. A filing whose region revenues do not sum to its consolidated revenue within 0.5% is marked partial with the numbers in the reason; nothing is adjusted to make it reconcile. Across the June 2026 filing season, 95.9% of the filings that carry a region table reconcile, and 91% of all filings are clean.
• Regions are on the filer's own basis — customer location for most, shipping destination for some — and the basis sentence is stored and shown with the figures. The filer's label is kept verbatim; a small lexicon maps it to a key (JP, CN, TW, KR, US, NA, EU…) so two filers' "China" can be read together, and a label the lexicon does not know keeps no key rather than a guess. A sub-note such as 「北米のうち、米国は…」 is its own row, marked as a sub-note of its parent, and is never added to the region it sits inside.
• A filer that omits the region table says why — no overseas revenue, or domestic revenue above 90% — and that reason is stored. The absence is then a fact, not a gap, and no region row is invented for it.
• Named customers are every customer the filer discloses at ten percent or more of revenue, with the revenue booked from them, as written. Some filers give them in a table, some in prose; the source is marked. Fiscal years are named the Japanese way, for the calendar year in which they begin: the year ending March 2026 is FY2025.
• Fiscal roll-ups of customs data: Σ over the fiscal year's months of the published customs value for every partner the region key maps to. Only monthly flows are summed — customs values and quantities, visitor counts — and the API refuses to sum an index, a stock or a rate. Only complete periods are shown: a fiscal quarter or year with an unpublished month is left out, never summed short, and the months left out are listed.
• The commodity-to-company mapping is a platform classification, not an official source label. Customs records carry no company identity. A company is mapped to a customs line only where its own annual report describes that product as a reportable segment or principal product; the file is versioned in the repository with an owner and a review date, and every surface that uses it says so.
• Implied share = revenue the company filed for a region / customs exports to that region's partners over the same fiscal year × 100. An indicator of size and direction, never an accounting identity. A company ships from overseas plants, sells domestically, and books revenue on acceptance rather than shipment; the customs line includes its competitors and trading houses; and the company's region and the customs partner list are different definitions that share a name. An implied share above 100% is that caveat made visible. Only regions that name a place are joined — China, Taiwan, Korea, the United States, North America, Europe — and "Asia" never is, because one filer's Asia includes Japan and another's excludes China.
• Named customers and dependence. A listed company must disclose any customer worth ten percent or more of consolidated revenue and state the amount. dependence[filer, customer] = customer revenue / the filer's consolidated revenue × 100, both as filed for the same fiscal year; combined dependence is the sum over every customer that filer names. It cannot exceed 100%: a filing where it did was a parsing fault, and two gates now catch that class of error — a single customer larger than the filer's whole revenue, and a combined total above it. A company absent from the list has no customer at or above the threshold, which is not the same as having a diversified book. Where consolidated revenue has not been extracted the share is blank, never assumed.
• English customer names are looked up, never translated. The English name beside a filed Japanese one comes from the EDINET company registry where the buyer files its own annual report — which also yields a securities code, so the buyer's own page can be opened from the row — or from a small curated list, versioned in the repository with an owner and a review date, for government bodies, unlisted subsidiaries and foreign affiliates the registry cannot cover. Where no published English name exists, none is invented. Of 1,010 distinct customer names, 363 resolve to an English name and 132 are already in Latin script; the remaining 515 are shown as filed. A subsidiary keeps its own identity — Amazon Japan G.K. is not Amazon.com, and TEPCO Energy Partner is not TEPCO — because rolling a subsidiary up to its parent would state a relationship no filer disclosed.
• Customer names are never merged. They are shown exactly as each filer wrote them: Toyota appears as both 「トヨタ自動車(株)」 and 「トヨタ自動車株式会社」, and Samsung under three different strings, because that is what the filings say. Combining them would state a total no company disclosed, so search matches text and the page tells the reader to try more than one spelling.

• Two datasets sit behind this surface and they are not interchangeable. population-jp is the Basic Resident Register (住民基本台帳) as published by the Ministry of Internal Affairs and Communications: an administrative count of everyone on a municipality's register at 1 January, not a survey estimate, split three ways — all residents, Japanese residents and foreign residents. population-jp-history is the Statistics Bureau's System of Social and Demographic Statistics (社会・人口統計体系), which republishes census, population-estimate, vital-statistics and register figures on one prefecture grid back to 1975.
• Reference dates differ by series and are never mixed on one axis. Register counts are as of 1 January. Register flows — births, deaths, moves — cover the calendar year before that date, so the count at 1 January 2026 less the count at 1 January 2025 equals the flows dated 2025. Census and population-estimate figures are as of 1 October and are a different measure: the total population line and the registered residents line are close but neither is read off the other.
• Change rate: net change ÷ (population − net change) × 100. The register publishes the closing count and the change over the year, but not the population it started from, so the denominator is the published count less the published change.
• Natural and social change: (births − deaths) ÷ opening population × 100 and (net change − natural change) ÷ opening population × 100. Social change is not migration. The ministry defines it as net change less natural change, so it also carries naturalisations, losses of nationality and register corrections. In-migrants less out-migrants is a different figure and does not equal it for any prefecture.
• Foreign share: foreign residents ÷ all residents × 100, always over all residents whichever segment the table is showing — a share of one nationality within itself has no meaning.
• Aged 65 and over: (sum of the published five-year bands from 65 upward) ÷ all residents × 100. A small number of residents have no usable birth date on the register, so the bands fall slightly short of the published total — 43 people in 123.8 million nationally at 1 January 2026, but 1,258 of Hokkaido's 75,392 foreign residents. The shortfall stays in the published total rather than being spread across the bands, so a share computed from the bands is a share of everyone, not of everyone with a recorded age.
• Crude birth and death rates, on the register: births (or deaths) over the calendar year ÷ mid-year population × 1,000, where mid-year population = (population at 1 January + population a year earlier) ÷ 2. A crude rate is per thousand of the population that lived through the year, which is neither endpoint; the register gives both, so the mean of the two is used rather than the closing count.
• Crude birth and death rates, on the long run: births (or deaths) in year Y ÷ Japanese population at 1 October Y × 1,000. Different inputs, so a slightly different number from the register figure above, and the two are never drawn on one axis. The vital statistics count Japanese nationals, so the denominator is the Japanese population and not the total; the 1 October estimate is the mid-year population the vital statistics themselves use. The flow and the population are joined on the year, not on the reference date. This reproduces the Ministry of Health, Labour and Welfare's published rates — 6.0 births and 13.0 deaths per 1,000 for 2023.
• Population pyramid: the bars are published counts. share % = residents in the band and sex ÷ residents with a recorded age and sex × 100 — the denominator is the sum of the bands, not the published headcount, so the bars add to 100%. The gap between the two is stated under every pyramid. aged 65+ per 100 aged 15–64 = residents 65 and over ÷ residents 15 to 64 × 100; males per 100 females = male residents ÷ female residents × 100. Japan's profile is drawn behind a prefecture's as a dashed outline on shares only: two areas cannot share a count axis.
• The total fertility rate is the one published rate on this platform that is stored rather than calculated. It is the sum of birth rates at each single year of a mother's age from 15 to 49; its denominator, the female population by single year of age, is in no table held here, so it cannot be rebuilt from the counts on the page. It is therefore served exactly as the Statistics Bureau publishes it and carries the Official Statistic badge on that basis. Being a rate, it never sums across prefectures, and the ingest's reconciliation gate skips it. Prefecture figures are published for 1980, 1985 and then every year from 1986; the missing years are drawn as gaps. Vital statistics run about two years behind the register, so this series ends earlier than everything else on the page. The 2.07 reference line is roughly the rate at which a generation replaces itself — a reference level, not a published series.
• Two published figures that will not reconcile, disclosed rather than adjusted. The national age bands hold about 6,200 more foreign residents than the 47 prefectures band, because a prefecture leaves those people unbanded and the national row does not; summing the prefectures therefore gives a slightly smaller age total. And the Statistics Bureau's own ageing rate excludes people of unrecorded age from its denominator, so in census years it differs from 65+ ÷ total population by real amounts — 28.7% against 28.0% in 2020. Every rate the platform can rebuild from published counts it calculates itself and shows the formula for; the total fertility rate is the single exception, above.
• Index view: value[t] ÷ that series' value in the first year of the window shown × 100. The base is the first year in view, not a fixed year, so changing the range rebases the chart — the base is printed on the axis and in the export header. Foreign residents enter the register only in 2013, so on a window that starts earlier that line is based on 2013 and the others are not; the lines are then comparable in shape, not in level.
• Log axis: an option on the level views, not a default. Registered residents and foreign residents are two orders of magnitude apart, so on a linear axis the smaller line sits on the baseline with no readable shape. On a logarithmic axis equal vertical distances are equal proportional changes, not equal numbers of people; the axis is labelled "log scale" wherever it is on.
• Municipality level mixes four kinds of area in one column, and three of them overlap. Under each prefecture the workbook lists the prefecture, then designated cities and their wards, districts and the towns in them, and — in Tokyo — one 島しょ row covering the islands as well as each island town. Adding every municipality row together gives 160 million people in a country of 124 million. The 328 rows that are sums of other rows are identified by two independent signals (a grouping row's name is a strict prefix of the rows it groups; and the workbook is an outline in which a grouping row equals the run that follows it) and the result is proved by reconciliation — the 1,898 municipalities add to their prefecture exactly, in all three resident segments. Grouping rows are published here too, marked level: group, and are never included in a total.
• Small cells are suppressed. At municipality level the ministry withholds counts small enough to identify someone — 17,829 cells in the 2026 foreign-resident age workbook. A withheld cell is missing, not zero: a village with three foreign residents has three, and its age bands are simply not published. One Hokkaido village has every foreign age band withheld, so 100% of its foreign residents fall outside the bands, which is correct rather than an error. Across all municipalities the unbanded share is 0.155% of foreign residents and 0.005% of all residents.
• Six municipalities are carried on the register with a population of exactly zero — the villages of the disputed Northern Territories. Any per-capita figure has to guard against them; none is computed here.
• The ministry keeps only the current year's workbooks online — last year's file is deleted and its URL reused — so the archive of past releases here is the history.

• Why the House of Councillors and not the House of Representatives. The upper house's 45 prefectural constituencies (選挙区) are exactly prefectures — every prefecture on its own, except two merged pairs — so a prefecture headcount divides into a seat count with nothing left over and nothing counted twice. The lower house's 289 single-member districts cut through cities below the municipality level, and no boundary file on this platform can resolve them; that surface is not offered rather than approximated.
• The seat complement is law, not a statistic. 公職選挙法 別表第三 (Public Offices Election Act, Appended Table 3) as amended in 2018 and in force since the 2019 ordinary election: 148 district seats across 45 constituencies, plus 100 elected from a single nationwide proportional list, which no prefecture's population bears on and which is excluded here. The table carries no vintage and no freshness — it changes when the Diet changes it. It is held as a checked constant, cited to the Ministry of Internal Affairs and Communications on the surface itself, and self-checked on every request: 45 constituencies, 148 seats, every prefecture in exactly one constituency, and every complement even. Half of each constituency's seats are contested every three years (改選数 = 定数 ÷ 2, whole for every one), so the per-seat ratios are the same whichever complement is divided.
• Tottori with Shimane, and Tokushima with Kochi have been single two-seat constituencies since 2016 (合区). Their two prefectures are summed and they are never shown as four.
• Four denominators, because who counts as the electorate is the argument. adults18 is Japanese residents aged 18 and over, the franchise as it has stood since 2016; adults20 is Japanese residents aged 20 and over; japanese is Japanese registered residents of all ages; residents is everyone on the register, foreign nationals and children included. The last is not an electorate: it is the base most often quoted in the apportionment argument, and the gap between it and the first is itself a finding, since a prefecture with many foreign residents is allocated representation for people who cannot vote in national elections.
• One quantity is estimated, and only one. The register publishes five-year age bands, so the two single years 18 and 19 are taken as two-fifths of the 15–19 band: adults18 = Σ bands from 20–24 upwards + 0.4 × the 15–19 band. Every other year is a published count added as published. The surface serves the headline on all four denominators side by side so the influence of that one estimate is visible rather than asserted; on the January 2026 register it moves the widest disparity by 0.014×, against the 20-and-over basis that splits nothing.
• The register is not the electoral roll. Residents on the Basic Resident Register are close to, but not identical with, the people on the 選挙人名簿 — the roll applies a three-month residency requirement, carries overseas voters separately, and excludes people disqualified from voting. This is an electorate measured from the register, not a count of registered voters, and nothing here should be quoted as the latter.
• The formulas. per_seat = electorate ÷ seats; vote_weight = min(per_seat over the 45) ÷ per_seat, so the best-served constituency is 1.00 and every other is the fraction of one of its votes that a vote cast there is worth; disparity = 1 ÷ vote_weight, the figure the courts and the press quote; the headline 最大格差 is max(per_seat) ÷ min(per_seat). seat_share = seats ÷ 148 × 100, electorate_share = electorate ÷ total × 100, and over_representation = seat_share − electorate_share in percentage points, which sums to zero across the chamber by construction.
• The drift series is a counterfactual and is labelled as one. It applies the seat table in force today to every year of the fifty-year prefecture panel, using registered Japanese residents of all ages (indicator A2101, the only register count published on one basis for fifty years). It measures how far the population has moved under a map that does not move with it — not what the disparity was at the time, which was governed by whatever table was then in force. A year missing any prefecture is left out rather than compared against a different set of areas.
• A constituency with no count is null, never zero. If any prefecture in a constituency has no published figure the constituency's electorate is missing, and it is excluded from the totals, the extremes and the disparity rather than imputed. A constituency whose electorate is a genuine zero keeps that zero and takes no ratio: it can neither anchor the best-served end nor produce a division by zero.

• Nothing is recomputed. Every figure on the Financials page and under /api/v1/equity/financials/ is the value tagged in the company's own annual securities report (有価証券報告書) on EDINET: the filer's five-year summary (主要な経営指標等の推移) and its balance sheet, income statement, statement of comprehensive income, cash flow statement and statement of changes in equity, consolidated and parent-only. ROE, equity ratio, PER and payout ratio are the filer's figures — filers differ in how they compute them (average versus year-end equity, for instance) and this platform does not harmonise them.
• Percent fields. The taxonomy stores ratios as fractions (0.101 for 10.1%); fields named *_pct are that fraction × 100 and nothing else.
• Statement order and membership come from the filing's own presentation linkbase, so a statement prints line for line as the filer laid it out, including the filer's own extension line items. A line the filer marks with a negated label is one it prints with the sign reversed (a cost shown positive); the API flags it and the value is left as tagged.
• Standardised field names (revenue, profit, roe_pct…) are a mapping from element names, one entry covering the Japan GAAP element and its IFRS twin; every row names the element behind each field. Where a filer tags no standard revenue element — Toyota's summary uses its own — revenue is the first yen line of the filer's summary table and the row says so (revenue_source = first_line). Bank and insurer "revenue" is 経常収益 (ordinary income), as those filers report it.
• Restatements are kept. Each filing restates five fiscal years. The company panel takes each fiscal year from the latest accepted filing that covers it and names that filing on the row; ?as_filed_in=YYYY serves one filing's five years exactly as first published, which is the point-in-time view. Fiscal-year labels are the filing's period end shifted by whole years, so a filer that changed its year-end inside the window is labelled by that arithmetic, not by its old year-end.
• The only derived numbers on a statement are the change columns: change = current − prior on the tagged values and change % = change ÷ |prior| × 100, shown as — where the prior value is missing or zero.
• Labels. Japanese labels are the filer's own. English labels are the filer's own where the filing carries one; otherwise a readable form of the XBRL element name, marked derived — never a translation of the Japanese by this platform.
• Gate. A filing is accepted as clean when its tagged balance sheet satisfies assets = liabilities + net assets on every basis it reports, and its summary's net assets do not exceed total assets; otherwise it is partial with the reason stated, and a cross-section says which. A filer whose statements are not tagged (US GAAP filers tag them as text) still has its summary figures.

The Screener and the "Calculated Ratios" block on each company's Financials page are the one place this platform computes a number from the filed statements. Same rule as every other derived figure: no badge, the formula on the page, every input named, and the filer's own figure beside ours wherever the filer prints the same ratio.

• ROE = profit attributable to owners of parent ÷ average of opening and closing equity attributable to owners × 100. ROA = the same profit ÷ average total assets × 100. Averages are the convention Japanese filers use for their own ROE; a filing whose opening balance is not tagged gets no ratio rather than a closing-balance one. Across the current universe our ROE is within 0.5 pp of the filer's own for over 99% of companies; the difference is shown per row, and a gap over 1 pp is marked. Every remaining difference is a filer convention, not an error: all six companies that differ by more than 2 pp divided by closing equity rather than the average, and our figure recomputed on their basis reproduces each of them exactly. Filers disagree with one another here — Chiyoda uses the average and matches this platform at 123.1%, Kodama Chemical uses the closing balance and prints 82.8% where the average gives 144.9% — which is why one convention is applied to every company and the filer's own figure is always shown beside it.
• A return is not calculated on a negative base. Where average equity over the year is zero or negative the ROE is withheld and the company is flagged negative equity instead. Dividing a loss by negative equity inverts the sign: Japan Display closed FY2026 with equity of −¥7.5bn against +¥6.7bn a year earlier, and its ¥19.8bn loss over that negative average would otherwise read as an ROE of +4,570% and rank first in the market. The test is applied to the denominator actually used, so a company that recovered from negative equity during the year still gets a ratio; across the universe this withholds exactly the three companies whose own filings also decline to print an ROE. The equity ratio is still shown for these companies — it is negative, which is the point, and it matches the filer's own figure.
• Where the base is not available, no ratio is invented. US GAAP filers publish their statements as text, so their equity comes from the five-year summary, and only from a line that names the owners of the parent — Komatsu, ORIX, Fujifilm and Omron all reconcile to their own published ROE within 0.05 pp on that basis. Nomura tags only equity including minority interests, which is the wrong base for a return to shareholders, so this platform shows no ROE for it and prints the company's own figure instead.
• Equity attributable to owners (自己資本): under IFRS the tagged element; under Japan GAAP net assets less non-controlling interests less subscription rights to shares. A balance sheet that prints no such line has none, so an absent subtrahend is nil — the only case in which an absent tag is treated as zero, and only for a subtractive component under a total that is present.
• Revenue and profit are the filer's own summary lines, resolved as on the key-indicators panel; banks and insurers report 経常収益 as revenue. Operating income is the summary's where printed, otherwise the income statement's; banks, insurers and most IFRS filers print none, so their operating margin is —.
• Margins: operating income ÷ revenue, profit ÷ revenue. Asset turnover: revenue ÷ average total assets. Growth: current ÷ prior − 1 from the same filing; profit growth is not computed off a prior-year loss. Cash conversion: operating cash flow ÷ profit, not computed for a loss. Free cash flow is the simple definition, operating plus investing cash flow, and is labelled as such. Cash / assets: cash and equivalents ÷ total assets.
• Implied valuation. This platform holds no prices. Where the filer prints its own year-end PER, an implied price = PER × EPS gives an implied PBR (÷ book value per share) and an implied dividend yield (DPS ÷ implied price). Both are labelled implied and are only as current as the filer's year-end. Per-share dividends are printed in the reporting company's own summary table, so the yield is computed entirely inside that table and never mixes the group's per-share figures with the parent's. A share split between the fiscal year-end and the filing can still leave the paid dividend and the restated EPS on different share bases; the filer's own payout ratio exposes this, and where it disagrees with DPS ÷ EPS by more than 25 pp no yield is derived and the row says why.
• Basis and ranking. Consolidated where the filing carries consolidated statements, parent-only otherwise; every row says which. Rankings use one filing per company, its latest accepted annual report; companies without the ranking metric are left out and counted on the page. Filters are floors and caps in each metric's own unit.

A rank across the whole listed market answers almost nothing: a 3% female board is unremarkable among 3,700 issues and conspicuous inside TOPIX Core30. The Peer Groups page and the cohort parameter on every equity screen restrict a cross-section to a peer group before anything is ranked. Every figure compared is the same one its own page publishes; the statistics about a cohort are calculated here and carry their formulas.

• The classification is not ours. Market segment (Prime, Standard, Growth), the 33- and 17-industry classifications and the TOPIX scale band (Core30, Large70, Mid400, Small 1, Small 2) are taken exactly as Japan Exchange Group publishes them in the listed issue list (東証上場銘柄一覧), and are never inferred, recomputed or back-filled. The issues carrying a scale band are the TOPIX constituents — 1,636 of them at 2026-08-31. This platform does not compute index membership and does not maintain an index.
• Membership is a vintage. Each accepted read of the JPX file is stored under its own effective date and the SHA-256 of its bytes, and a stored vintage is never rewritten: a revised file lands beside the first, so what a cohort contained on a given date stays recoverable. Index reviews, segment migrations, listings and delistings accumulate as history from the first read forward. Neither publisher offers back-history, so a request for a date before collection began answers with nothing rather than quietly returning today's membership.
• Index membership is not published here. The Nikkei 225 constituent list is Nikkei's copyrighted work and may not be redistributed. Where it is held it is held for internal comparison only, behind an explicit switch, and it is absent from the public catalogue, the API and the assistant tools unless a deployment is entitled to it.
• Baskets are not stored. A basket of securities codes is carried entirely in the address bar (cohort=codes:8001,8002,…), which is what makes any comparison built on one a permanent, citable link. Names given to baskets are kept in the reader's own browser and are never uploaded.
• Median and quartiles are taken over the cohort members that report the measure, by linear interpolation between the closest ranks of the sorted values (the conventional method, R type 7): for n values the p-quantile sits at position (n − 1) × p. Percentile = members strictly below the value, plus half of those equal to it, ÷ members with a value × 100 — the mid-rank convention, so a company in the middle of its cohort reads 50 whichever way ties fall. vs median is the company's value minus the cohort median, in the measure's own unit; for a measure in per cent that difference is in percentage points.
• A company that does not report a measure is not a company reporting nil. Members without a value are excluded from the distribution and from every rank, listed separately with the reason, and counted on the page. They are never imputed and never treated as zero.
• Reference periods differ across a cohort. Each company contributes its most recent annual report and Japanese fiscal year-ends are staggered, so a cross-section carries no single as-of; every row shows its own period end. The board, register, financial-statement and cross-shareholding figures for one company can also sit on different filings, and each is labelled with the filing it came from.
• The distribution chart may cut its axis. Where a cohort's tails are extreme — operating margin across electrical-machinery makers runs from a four-figure negative to a four-figure positive — the plotted range is cut to the 1st–99th percentile so the shape is visible. Values beyond it are counted in the end bars rather than dropped, the caption says how many, and the table beneath carries every value in full.