Asking rent is an offer, not an outcome
A portal shows units still seeking tenants. It normally does not show the final rent, free-rent period, brokerage incentive, rejected applications, days vacant after removal, or units leased privately. The most visible listings may be the least competitive. Use asking supply to identify competition and features, never as the sole achieved-rent evidence.
Define the question precisely: expected rent, time to lease, concession, tenant profile, renewal probability and loss if the unit is vacant. One “market rent” number cannot answer all six.
Start with the subject's lease history
Request every lease, amendment, rent ledger, vacancy interval, advertisement, enquiry report, application outcome, concession and leasing invoice available for the unit or building. Reconstruct the effective rent after free periods and owner-paid incentives. A JPY 200,000 lease with one free month and one month of owner-paid brokerage over a two-year term is economically below JPY 200,000.
For a whole building, compare units of the same layout, floor and condition. Recent signed leases in the building are stronger evidence than an agent's estimate, provided they are arm's-length and the incentives are known.
Build a competing-stock sample
Search a tightly defined area and capture address, walking route, age, structure, floor, area, plan, aspect, condition, equipment, stated fees, concessions and listing date. Remove duplicates across agents. Recheck weekly so persistent inventory and withdrawals become visible.
Do not average unlike units. A new compact unit near an express stop and an older family unit across a major road face different demand. Use the sample to position the subject and to identify missing features, not to manufacture precision.
Read household evidence at the right scale
Official census and municipal statistics can show population, household size, age and movement. Housing and Land Survey data describe tenure and vacancy at broader scales. These establish the size and direction of potential demand, but not the achievable rent for one unit.
Connect the asset to a plausible household: single commuter, couple, family, student, corporate lease or older resident. Test travel time, daily shopping, childcare, floor access, storage, noise and layout from that tenant's perspective. Demand follows a usable product, not a ward population total.
Interview operators with an audit trail
Ask several active leasing managers for recent achieved cases, leasing days, rejected price points, typical incentives and tenant objections. Record the date, person, property specification and whether the firm handled the transaction. Treat unsupported opinions as hypotheses.
Use consistent questions so answers can be compared. An agent saying “JPY 190,000 is easy” should also state expected days, required condition, advertising fee and evidence from a similar signed lease.
Run a controlled pre-leasing test when possible
For a vacant or soon-to-vacate unit, agree a launch price, photographs, condition, response standard and weekly reporting. Track qualified enquiries, viewings, applications, objections and source. Change one major variable at a time. A price reduction made simultaneously with renovation and new photography does not reveal which change worked.
Stop the test before extended vacancy destroys more value than the information is worth. The objective is a signed, financially acceptable lease—not proof that the original asking rent was correct.
Convert evidence into underwriting
Use base, downside and severe achieved rent, leasing period and incentive. Connect each to evidence. Add restoration and brokerage as cash items, then calculate effective rent over the expected tenancy. Review renewal risk separately.
After purchase, compare every actual lease with the underwriting and retain the result. Over time the owner builds a proprietary achieved-rent series without publishing or relying on another real-estate site's claims.
Primary sources
- Statistics Bureau of Japan — Population Census: https://www.stat.go.jp/data/kokusei/2020/index.html
- Statistics Bureau of Japan — Housing and Land Survey: https://www.stat.go.jp/data/jyutaku/2023/tyousake.html
- e-Stat — Official Statistics of Japan: https://www.e-stat.go.jp/
- MLIT — Real-estate information library: https://www.reinfolib.mlit.go.jp/
Reviewed 23 August 2026. Signed subject leases and documented local leasing results control; official statistics provide context rather than a unit-level rent.
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