This article dives deep into why the Japanese Blu-ray of Kill Bill is so sought-after, the technical differences you need to know, and how to spot a legitimate copy.
Japanese physical media is world-renowned for its presentation. The (originally released on DVD but often paired with Blu-ray collections) are legendary for their "goodies":
Tarantino stated this was an artistic choice to avoid an NC-17 rating and to homage the brutal black-and-white battles of Samurai Rebellion . However, the real reason was the MPAA. The sheer volume of arterial spray, severed limbs, and gore was too much for an R-rating. By draining the color, the violence became "stylized" rather than "visceral" in the eyes of the ratings board.