Early deals included the acquisition of U.S. publisher Ziff Davis and a joint venture with Rupert Murdoch's News Corp. to attempt to break open the Japanese satellite broadcasting market. Over the years, the company has invested in a string of startups and today owns stakes in two of China's biggest Internet companies: Renren and Alibaba.
But perhaps more so than the Internet, the cellular market is where Softbank has made its mark.
In the mid 2000's as Japan looked to increase competition in the domestic telecom sector, Softbank had finally won enough respect from the government to be awarded a mobile license -- something that has never just come down to money in Japan -- but it wasn't the type of spectrum the company wanted.
Despite pressure from Softbank, no more spectrum was forthcoming so the company pounced when the U.K.'s Vodafone decided it wanted to leave Japan. Vodafone had entered Japan a few years earlier with the acquisition of the number-three carrier but had limited success in pushing global phones and services to finicky Japanese consumers.
Softbank acquired Vodafone Japan and within months the mobile phone market got the same jolt of competition that the DSL market had gotten five years earlier. The company took on significant amounts of debt to make the acquisition but managed to pay it off by slowly selling down its stake in Yahoo.
Masayoshi Son has spoken frequently of his great admiration of Apple founder Steve Jobs and was responsible for introducing Japan to the iPhone in 2008. At the time, Japan's cellular market was its own little bubble, full of domestic handsets that didn't sell overseas and with none of the foreign brands that were fast becoming popular worldwide.
Initially, analysts were unsure how the iPhone would be greeted by Japanese consumers, so Softbank's commitment to launch the phone was a bet of faith, but the phone proved to be a success. Its introduction woke Japanese consumers up to the existence of quality beyond the nation's shores, and sent Japanese handset makers into a tailspin from which they are yet to recover.
Now the iPhone is the hottest handset in Japan and even though its also carried by a rival carrier, Softbank continues to be its greatest flag waver in Japan.
Recently, Softbank announced a deal to acquire data-centric mobile operator eAccess for a deal worth $2 billion. The acquisition, when complete, will make Softbank the number-two carrier in Japan.
If Softbank does acquire third-ranked U.S. carrier Sprint, the U.S. could be the next market to witness Masayoshi Son's bold business style.