Back to back ninjas! (If the videogames of my generation taught me anything, it's that you can never have too many Ninjas.) First female character as well, but she'll be getting some company real soon.
As a momentary aside, I have to say that gaming culture needs to be careful on how it deals with ladies. I got to "I," and realized that there had yet to be any female characters on the list.
I had a few planned, but so far it's been a real sausage fest. Seeking inspiration, I did a search for the top female videogame characters. Man. There are way too many "Hottest Female character," lists and not enough "most badass female character," lists.
I like pretty ladies as much as the next guy, but come on. I'm guessing the female "hottest," lists outweigh their male counter parts 10 to 1. And honestly, male videogame characters are almost always designed to look impressive, powerful and ready to kick heads in. Female characters are all too often designed simply to titillate. I know there are some notable exceptions on both ends, but looking at the industry as a whole, there is some growing up that needs to be done.
But enough about gender depictions in mass media! Ibuki is awesome. She's a ninja, has a pet tenuki, and some really baffling cutouts in her pants. Go ninja girl! I can't play with you worth a damn, but you still have an awesome design!