The more I think about it, the more I think it might be better if we left Hakuba out of this one. It seems better for someone like Ty Lee or Archer (Iseei's friend) to put her in her place because she directly did something to bug them. It'd be difficult to come up with a good motive for someone to kidnap blondie, particularly since Ty Lee doesn't seem like the kidnapping type, and I have no clue if Archer would get revenge for Issei's kidnapping by doing some kidnapping of his own...

Besides, if we leave Hakuba out of it, then he can be there to comfort her when she gets all upset due to being bested~