Eu encontrei as informações deste site , que contém a entrevista dada pelo produtor de animação para essa foto:
One of the most striking sequences in both Kill Bill films is the backstory sequence of Deadly Viper Assassination Squad member O-Ren Ishii. Tarantino collaborated with Production I., the anime studio behind Ghost in the Shell, Blood: The Last Vampire and segments of The Animatrix, to craft this bloody, hand-drawn expansion of mythology, an setup that dimensionalizes Ishii and her violent practices.
Animation producer Katsuji Morishita explained to CGSociety that, "Quentin himself came to our studios to meet with us in person. He already had the image and style in mind, and wanted us to make the animation based on his script. He actually acted out the performances of the characters to be animated in front of us. There were 4 sequences in all, and the production period was 1 year. Those 4 sequences would've been extremely difficult to make in live-action. Even if it had been possible, it would've taken tremendous amount of budget and work."
No kidding -- the price tag for the blood alone would have been seven figures.