About this site
Who writes this
I am a licensed real estate broker in Japan (takken-shi). I worked for ten years at a listed Japanese real estate company, then left. Today I work a salaried job and own rental property myself, so I deal with tax returns, loans and tenants as an owner, not only as a professional.
I do not sell property, arrange loans or introduce agents. The articles explain how the Japanese system works, using figures from the calculators on this site.
Why the tools run in your browser
Salary, loan balances and family details are sensitive. The simulators calculate everything on your device and do not send what you enter to a server.
What is here
A one-room condo simulator (monthly cash flow, tax refund from a rental loss, 35-year projection, printable reports) in English and Chinese, a furusato nozei calculator that handles rental income, and practical articles on investing in Japanese condos.
How the figures are calculated
Income tax and resident tax follow the rules for the 2026 tax year, including the basic deduction that changes with total income, the employment income deduction and the limit on offsetting land-loan interest (Special Taxation Measures Act Article 41-4). Depreciation of used buildings uses the simplified useful-life method of the Ministry of Finance ordinance. Capital gains on a sale use the long-term (20.315%) and short-term (39.63%) rates.
Every number in the articles is produced by the same calculation as the simulator, and the site’s automated tests check that the articles and the calculation agree. When tax rules change, the calculation and the articles are updated together.
Why these articles exist
Foreign residents in Japan are often offered one-room condos as a way to save tax, usually with a sales simulation prepared by the seller. Independent explanations in English are hard to find, and the Japanese tax rules behind the numbers (loss offset, the land-interest restriction, the simplified useful life, the 5-year rule on sales) are rarely explained together.
These articles follow one example from purchase to sale so you can see where each number comes from, including the years when the numbers turn against you.
How to use the simulator
Start with the price, rent, management fee, repair reserve, loan and your salary. The monthly balance and the estimated tax effect update as you type. Then open the tax tab to see each year, and the 35-year tab to add events such as vacancies, a rate rise or a sale. The reports can be printed or saved as PDF to compare with a seller’s proposal. The interface can be switched to Chinese or Japanese; the results are the same.
Questions about the site
Is it free? Yes. The simulators and articles are free and need no registration. The site is funded by advertising.
Where is my data? Inputs on the English and Chinese simulator stay in your browser on your device. Clearing your browser data removes them. Nothing you type is sent to a server or to the advertisers.
Can I share a result? Print the report or save it as a PDF. There is no account needed.
What this site does not do
The articles and tools explain how the Japanese system generally works. They are not tax, legal or investment advice for your situation. For your own return or a specific purchase, check with the tax office, your municipality, a licensed tax accountant or a judicial scrivener.
Contact
Run your own numbers
Enter the price, rent, loan and your salary to see the monthly cash flow, the tax refund and a 35-year projection. Runs in your browser.