TOKYO -- Prices of secondhand condominiums in Greater Tokyo are rising thanks to brisk investment activity. The value of used detached houses, however, is stagnating. This has some experts concerned about the true state of housing demand -- and what it says about the Japanese economy.

The price of used, wooden houses on 100-sq.-meter to 300-sq.-meter properties in Greater Tokyo averaged 29.52 million yen ($235,708) in June, according to real estate research company Tokyo Kantei. For the past year, the price has been hovering around 29 million yen; this was the first time in three months that it registered a month-on-month drop.