How to Read Japan's Published Land Values and Actual Transaction Prices — Verifying a Condo's True Worth Yourself

You're considering buying a condominium in Japan. The broker says the price is "in line with the market." You ask why. The answer: "It matches the local average."

Can you verify that average yourself?

Here's something most foreign buyers — and many Japanese buyers — never learn: with public data alone, you can build the foundation of an independent price estimate. Two numbers do the heavy lifting: rosenka (published land value) and actual transaction prices.

Understand these two, and the broker's word "market price" stops being a black box.

1. What Rosenka Is — And What It Isn't

Rosenka is the land value per square meter along every street in Japan, published by the National Tax Agency each July. It's the tax base for inheritance and gift taxes.

Critical point: rosenka is not the market price.

Rosenka is typically set at roughly 80% of the published standard land price (koji-kakaku) and roughly 70–80% of the real market price. Divide rosenka by 0.8 and you approximate the standard price. Divide further and you get closer to market reality.

Many buyers miss this. The broker says, "Even by rosenka, this price is reasonable." But rosenka is a tax valuation, not a market observation. It tells you a floor, not a fair price.

The actual market price sits above rosenka, shaped by location, building age, view, management quality, and timing.

2. Listing Price ≠ Transaction Price

The second number is the actual transaction price.

What you see on property portals — SUUMO, HOMES, At Home — is the listing price, the seller's wish. It is not the price the market paid.

This distinction matters. Listing and transaction prices often differ by 5–15%. If you negotiate from the listing price, you've already accepted the seller's starting frame.

Two public databases let you see real transaction prices:

REINS Market Information, operated by the real estate distribution bodies designated by Japan's MLIT. It shows anonymized historical transaction prices. You can't identify specific units, but you can see what similar properties — same district, same age band, same size — actually sold for.

Land General Information System (Ministry of Land, Infrastructure, Transport and Tourism), which publishes transaction data gathered through buyer surveys.

Cross-reference these, and you start to see the real distribution: what a 70 m² unit in a 20-year-old building in that district actually closed at.

3. Reading Rosenka and Transaction Data Together

Each number alone is limited. Rosenka tells you the tax-valuation floor of the land. Transaction data tells you what the market accepted in the past. Put them together, and you can locate today's asking price inside a real context.

A practical approach:

• Estimate the land share of the condo using rosenka × your unit's proportional land share × a correction factor (around 0.8 to approach market level)
• Compare the total asking price against the median transaction price for similar units in the area
• Adjust for age-based depreciation — Japanese condos typically retain around 60% of their new-build value after 15 years

Layer those three lenses, and the broker's phrase "market price" resolves into components you can examine one by one.

You notice something uncomfortable: "market price" is often a convenient phrase for both the seller and the broker.

4. Why Doing the Math Yourself Matters

"Shouldn't I just leave this to a professional?"

The point isn't to replace professionals. The point is to change the conversation. A broker who hears, "Based on rosenka, this feels slightly above the area's typical pricing — how do you view that?" responds differently than a broker who hears, "Is this a fair price?"

Negotiation is an information game. The broker has every number. If you have none, you take the asking price. If you know even the basic geometry of rosenka and transaction data, the ceiling of the price drops.

5. The Limits of Public Data

Public data has boundaries.

Rosenka reflects prior-year valuations. Transaction data lags the current market. In a rapidly moving market, both trail reality. And public data says nothing about management quality, view, floor, noise, or renovation history.

This is exactly why a buyer needs more than raw data. Public-data estimates need to be combined with an independent qualitative read of the specific unit.

Brokers are parties to the transaction. Their "market price" is framed by closing the deal. Structurally, they have no incentive to volunteer information that works against the sale.

What a buyer needs is an analysis without a stake in the outcome.

Key Takeaways

• Rosenka is a tax valuation, not a market price. Divide by 0.8 to approach the standard price level.
• Listed prices on SUUMO are sellers' asks, not transaction prices.
• Use REINS Market Information and the Land General Information System to see real closed prices.
• Combining rosenka with transaction data reveals the structure behind a broker's "market price."
• Public data has limits. Qualitative evaluation of the specific unit must be layered on top.

You've heard the broker. It's time to hear your side.