ITT: Anal Princesses BESIDES Iori.
She's saving "it" for Kyosuke, but she'll offer you all of her other holes, butt included.
So, her front half isn't moving. Which means they probably super-imposed the lower half moving on top of a still frame.
Which means that there is some guy whose job it was to just draw her disembodied legs shaking like that.
I wonder what that man's life is like. I wonder if his parents are proud of him.