Modern anime doesn't do anything for me.
With these two things in mind, I'm not sure why Kirsten Dunst dressed up in an anime outfit singing 'Turning Japanese' should be so sexy. I think it's some of the looks she gives the camera. It doesn't hurt that she has the same type of lips as Debbie Harry, who I always thought was hot.
NSFW due to anime boobies.
EDIT: Odd, the company involved seems to have removed the video. Link changed to a YouTube link; it's not as high-quality, but still good.