Japanese based research firm Impress R&D has released a report showing that the iPhone has 46.1% of the Japanese smartphone market. Impress goes onto break down individual iPhone models stating that the iPhone 3G has a 24.6% share whilst the 3GS has a 21.5% share.
MobileCrunch offers some analysis pointing towards aggressive advertising via print and TV adverts and competitive pricing from the exclusive carrier Softbank.