Rider War: Prologue (ライダー大戦・序章 Raidā Taisen: Joshō) is the thirtieth episode of Kamen Rider Decade. It is the first part of the series' endgame, the World of the Rider War. On October 4, 2009, TV Asahi began a re-broadcast of the series from beginning to end at 6:30 am timeslot. When episodes 30 and 31 were rebroadcast on May 2 and 9, 2010, respectively, they were recut with some scenes extended and others cut, labeled as "Special Edition" (特別編 Tokubetsuhen) versions, though almost no differences were present for this episode.