Oi. Accepting without knowing the conditions? Quite... brave.
Anyway, the premise reminds me of Bride of the Wolf King (Ookami heika no Hanayome), although the circumstances were different and the heroine is the complete opposite. I'm looking forward to more chapters, thanks for the translation!
I already don't like the emperor. Whatever assumptions he has about assassins, HE went to find HER. To HIRE her. Even if he said it only to test her, it was a shitty, manipulative thing to do. Not to mention stupid.