Remember Sony Japan’s unusual promotion campaign for an 8-inch netbook (or ultra-mobile PC, as the Japanese like to call these devices) from December 2008? The target group was amused with the campaign. And it appears the marketing coup helped Sony actually sell the Vaio P, as the company today updated its Japanese site with yet another teaser for yet another “mysterious” netbook.

All that Sony says on the site is that the device will be a “VAIO New Ultra Mobile”, meaning we can expect another sub-10-inch netbook (there is no info on specs, price, or release date). And if you live in Japan, you can register for a coupon that you can use when you buy the device. Sony will likely run similar campaigns again in other countries in the next weeks.