Okay, so I'm thinking to rework Jaden's profile like this:

I think the encounter with the Rokushiki user should happen earlier in Jaden's life than when it did. Perhaps said user was actually a member of The Marines, perhaps even a CP-9 operative, but went rogue to become a pirate. His crew raided Jaden's city, and in trying to protect the librarian, he was taken down by said Rokushiki user's more advanced technique. 

As far as the operative knows, Jaden's dead, and the librarian is among those taken as slaves. I might also make the librarian younger, if only so the pirates would find her more useful. So, using this new anonymity to travel the world and search for the librarian and the other people the pirates enslaved. Along the way, he's hoping to find more knowledge of techniques that he could use against the pirates, especially their captain. 

Which would bring Jaden to this fighters pit. There's more, but I'll PM it