Question Author
Well, after a bit of research, I found the answer myself, on www.killbill.net:
"The guitarist of a Japanese group called HOTEI is credited for making the music for the Kill Bill trailer. Hotei Tomoyasu was the music supervisor for the soundtrack of the yakuza picture, "New Jingi Naki tatakai." He has worked with Michael Kamen, Brian Setzer, David Bowie, etc. and exchange. He has also participated in "Merry Axemas" which Steve Vai, and "Happy Xmas". Moreover, this guitarist has performed in the closing ceremony of the Atlanta Olympics."
What's more, you can download the music (legitimately) from www.superhappyfun.com/birthday.