Casio Computer Co. will become the first Japanese company to market radio-controlled watches in China by selling high-end wristwatches in Beijing, Shanghai and other major Chinese cities from early September, Casio officials said Wednesday.Casio will sell its radio-controlled analog wristwatches under the Oceanus brand and aims to post annual sales of ¥4 billion in business 2009, the officials said.Prices have yet to be set, but the watches are expected to sell for ¥50,000 to ¥100,000.Citizen Watch Co. and other Japanese makers are likely to follow suit.Radio-controlled watches maintain accuracy by picking up signals broadcast from transmitters linked to atomic clocks in several locations across the world, including Mount Otakadoya, Fukushima Prefecture, Mainflingen near Frankfurt in Germany, and Fort Collins, Colo.