Softbank, which is currently undergoing a $12 billion acquisition of Vodafone Japan, plans to spend another $2.1 billion on mobile infrastructure this year to increase the number of 3G base stations and facilitate a faster migration of 2G subscribers to 3G services. The service provider is also partnering with Yahoo Japan to deliver services and will introduce Microsoft Windows Mobile devices later this year. Meanwhile, NTT DoCoMo, which controls more than half of the mobile-phone market in Japan, is trading at near all-time lows. The Japanese market is hitting a penetration rate of about 75 percent in a fiercely competitive market. That's why Vodafone is leaving, but Softbank is willing to invest a boatload of money to turn Vodafone Japan around.