Like quite a few of the posters before me, I wasn't sold on the story's premises of honor and duty; not because of an inherent prejudice of mine, but because the story itself sent rather mixed messages.
Partially this felt intentional. I think the narrator was supposed to be unreliable - believing in a fantasy of honor when she's really nothing more than a slave, with a bomb in her head ensuring her obedience. The problem is, as was also pointed out before, if she really believed in the honor system she should have taken her own life (just like her father did) before debasing herself. And the ending seems to indicate that the only thing that kept her obeying her own rules was that she was forced to.
So, is this a story trying to create a deliberate irony, about a slave who entertains an illusion of honor until it no longer suits her? If so, it did so in a confused way, introducing the huge red herring of her gender into the fray. I guess the fact that she was a woman gave her a crutch - when she says early on "he treats me as a woman first, samurai second" (or something to this effect), she is denying the reality that her would treat any samurai with equal disdain. Perhaps. But the story doesn't really give us the information we need.
Similarly, the action bit at the end felt like a distraction. Cool fighting moves, an underestimated single heroine who manages to fight a bunch of Yakuza (but spare the life of the one who's a schoolkid)? That belongs in the land of pulpy action movies (in fact, it felt like an abridged version of the last part of Kill Bill volume 1). Now, Kill Bill itself is a brilliant film that uses the conventions of pulp action to actually say something profound about violence. Is this story aiming at the same? That makes no sense, as most of the first half is devoted almost exclusively to her complaints at her treatment, and the action scene comes late and, as I said, feels out of place.
So, at the end, this story was simply deeply unsatisfying to me. I'm not sure what it was trying to do, but unless it was trying to make me confused and unhappy about it, I don't think it succeeded.