Skelly designed the appearance of the pseudo-3D special stages, based on a tech demo created by Naka. The special stages were created out of pre-rendered 3D polygons, video of which was compressed and halved vertically and horizontally to fit in the game cartridge. "Sonic 2" also introduced Sonic's sidekick Tails, a flying two-tailed fox, inspired by Japanese folklore about the kitsune and created by level artist Yasushi Yamaguchi. Sega of America objected to the character's name, Miles Prower (a pun on "miles per hour"), so he was given the nickname Tails as a compromise. Masaharu Yoshii served as director. The staff increased the speed of "Sonic the Hedgehog 2" compared to the first game.