Ninja Scroll is a movie that starts in ancient Japan. It's kind of hard to explain this movie, because there are several twist and turns here and there. I suggest you buy this movie and watch it for yourself.

This is "Kagero". She's a "Ninja woman" who has a special ability to involunatarily poison someone that touches her. Once the person just poisoned a little while later, they die, Except for a person who already is poisoned. Then she works as a counter effect for the poison.