How to unlock iPhone 4 iOS 5.1.1 BB 4.12.01 Softbank Japan?

I got an iPhone 4 locked to Softbank japan baseband 04.12.01. If you know any way to unlock / jailbreak lease help me out.
Thank you
>>> How to unlock iPhone 4 iOS 5.1.1 BB 4.12.01 Softbank Japan?