It’s big in Korea, it’s probably big in China’s grey market, and the iPhone continues to be big in Japan. According to a report [JP] released by Tokyo-based research company Impress R&D, the iPhone has captured a whopping 46.1% of the domestic smartphone market.

For this year, Impress sees the 3G commanding 24.6% in this segment, while the 3GS contributes another 21.5%. The 3G was introduced in Japan in summer 2008 (the 3GS followed earlier this year). Sources in Japan say that the iPhone user base in Japan now stands at 3 million, which is an impressive 10% of the global userbase.

Three models from Willcom, a Japanese mobile phone carrier, are ranked 3 to 5. The HTC HT-03A (aka HTC Magic), the first Android phone in Japan, made it to No. 10 (2.3%). The BlackBerry Bold, which is offered by Japan’s No. 1 carrier Docomo, is one rank behind with 1.2%.

A major reason for this development is the hyper-aggressive marketing strategy SoftBank Mobile, the iPhone’s exclusive carrier, pursues in Japan: TV commercials virtually around the clock, print ads in major media, super-competitive pricing etc. do have an effect, it seems.

On the other hand, I’ve never seen any of this coming from Docomo for Android or BlackBerry, so it’s no wonder virtually no one in Japan (where I live) knows what these devices actually offer – apart from geeks, obviously.