Japan SME Acquisition Index — Methodology (v1.1)
What the index measures
The Japan SME Acquisition Index tracks the market conditions faced by an
individual acquiring a small business with premises in Japan: how many
candidate properties change hands, at what price, and how large the
low-cost ("akiya") segment is. It is computed exclusively from Japanese
government records — no proprietary listings, no surveys.
Source data
- MLIT Real Estate Information Library (不動産情報ライブラリ) — individual transaction records (取引価格情報 + 成約価格情報), API endpoint XIT001, 2010–present, all 47 prefectures.
- e-Stat national census — municipal population, day/night ratio, age structure (used for per-capita normalization only).
- e-Stat SSDS municipal dataset (社会・人口統計体系) — vacant-home stock (Housing & Land Survey 住宅・土地統計調査, 5-yearly), taxable income and taxpayer counts (municipal tax statistics 市町村税課税状況等の調, yearly), and internal migration (Basic Resident Register 住民基本台帳人口移動報告, yearly).
- ECB / Frankfurter daily FX — USD overlay.
Definitions
| Term | Definition |
|---|---|
| House transaction | A record of type 宅地(土地と建物) — land with building |
| Condo transaction | 中古マンション等 |
| Old-house ("akiya proxy") transaction | House transaction where the building was 30+ years old at the transaction date (戦前 buildings counted as 80y) |
| Low-price house | House transaction at ≤ ¥5,000,000 total price |
| Akiya proxy share | old-house transactions ÷ all house transactions in the period |
| Akiya mobilization ratio | old-house transactions in the latest full year ÷ vacant-home stock from the latest Housing & Land Survey. Measures how much of the vacant stock actually trades |
| Price-to-income ratio | municipal median house trade price ÷ average taxable income per taxpayer (課税対象所得 ÷ 納税義務者数, latest year). Income is per taxpayer, not per household |
| Net migration | registered move-ins − move-outs in the latest calendar year (all nationalities); the rate divides by census population |
The "akiya proxy" is intentionally conservative: Japan has no national
registry of akiya sales, so we use aged-building transactions actually
recorded by MLIT as the observable trading segment of the akiya stock.
Aggregation
- Records are aggregated per municipality × quarter × type group.
- Municipal medians are exact within each quarter. National and yearly medians are count-weighted medians of municipal medians (approximation; error is small because municipal cells are numerous).
- Designated cities (政令指定都市) are reported at city level by merging their ward records.
- 5-year CAGR per municipality is computed on yearly median house prices, and only where both endpoints have ≥ 10 house transactions.
- Trend labels:
up≥ +2%/y,down≤ −2%/y, otherwiseflat;insufficientwhen the CAGR gate fails. - Quarters with fewer than 10,000 national house transactions are treated as not yet fully reported and excluded from the headline.
Known limitations
- MLIT transaction data is survey-based and covers a subset of all transactions; coverage varies by municipality.
- Median composition shifts (mix of urban/rural deals) move the national median independently of like-for-like prices.
- Building age is missing on some records; such records never count as old-house transactions (biasing the akiya share downward).
- The Housing & Land Survey publishes municipal vacancy figures only for larger municipalities; the mobilization ratio is blank elsewhere. Its survey year (currently 2023) differs from the transaction year, so the ratio mixes a slow-moving stock with the latest year's flow.
- Taxable income per taxpayer is not household income: non-taxpayers are excluded, so it runs higher than census household figures. Use the price-to-income ratio for comparisons between municipalities, not as an absolute affordability threshold.
Versioning
Methodology changes bump the version and are listed in the changelog at
https://www.sme-nexus.com/en/data/methodology. Dataset releases are quarterly.
Changelog
- v1.1 — added municipal socio-economic indicators from e-Stat SSDS: vacant-home stock and vacancy rate, akiya mobilization ratio, taxable income per taxpayer and price-to-income ratio, and net internal migration (count and rate).
- v1.0 — initial release (MLIT transactions, akiya proxy, USD overlay).