ComScore Japan has drafted in Maru Sato, most recently managing director of Expedia Holdings, to head up the company's first customer service operation in the Asia Pacific region.
Sato has also worked as managing director for Abacus Japan, Jupiter Media Metrix and AOL Japan.
Bob Ivins, executive vice-president of ComScore with responsibility for international activities, said: "Japan is the second largest advertising market in the world, and the region is home to some of the world's largest and fastest growing online populations. A strong local presence will support our global leadership in these critically important markets."
ComScore's Tokyo office will offer its syndicated online audience measurement product, ComScore Media Metrix, as well as other products analysing consumer's online behaviour.
ComScore services are used by clients including AOL, Microsoft, Yahoo!, BBC, Carat, Starcom, Universal McCann and Expedia.
In 2005 the company set up a European office in London and appointed Yahoo! research director Bob Ivins to run it.