There's a long back story here I'll post in a journal tomorrow (still need to polish it off)...But here's a general Idea.

He was raised in a small village deep in the mountains that was hard to find He was born to Two Kage level ninjas trained in binding techniques. He inherited their amazing abilities and is now considered the strongest in his small hidden village. When he was young a large group of Nukenin attacked his village and massacred many brave warriors. After that he moved on and received training from a secret group of ninjas known as the Gaminin. He learned many forbidden and secret techniques from them. Such as the ability to greatly infulence others through a secret technique.

The charm on his sword is one given to him by his best friend who died during the Nukenin attack. Since then He's dedicated his life to taking out the rouge nukenin and the Empire the serve.

http://www.furaffinity.net/journal/596944/ <-- Backstory