TOKYO: Dentsu has unveiled a new iPhone application, employing the device's GPS function to offer targeted promotional coupons from retailers to owners of the device in Japan.

Sogo & Seibu, a department store chain, has joined forces with the agency to launch the iButterfly service, with customer trials scheduled to begin in February.

The app works via a special butterfly icon, which appears on a user's screen as they approach a participating retail outlet.

They then "capture" the butterfly, enter the store and show their phone to staff to gain access to a promotional offer.

The launch of the iButterfly service reflects the growing popularity of the iPhone in Japan.

Tokyo-based research firm Impress R&D announced in August 2009 that the iPhone 3G and 3GS models had captured a combined share of 45.1% of the domestic smartphone market.

This success comes despite users' traditional preference for Japanese-built phones.

Analysis from MobileCrunch, an industry blog, suggested in December that this success was attributable to the "hyper-aggressive" marketing strategy adopted by SoftBank Mobile, the exclusive provider of the device in Japan.

Specifically, "around the clock" TV advertising was said to be driving brand recognition among consumers.

"I've never seen any of this [advertising] for Android or BlackBerry, so it's no wonder virtually no one in Japan (where I live) knows what these devices actually offer," MobileCrunch writer Serkan Toto argued.

Also commenting on the iPhone's success, Takeshi Natsuno, a professor at Keio University in Tokyo, said that the US and European mobile phone sectors had become "Japanised" over recent years, eroding the traditional technological edge enjoyed by domestic manufacturers.

This in turn has made users more willing to buy non-Japanese mobile phones.

Data sourced from Nikkei/AFP/MobileCrunch; additional content by Warc staff