The notion of 13 Riders is apparently a homage to the original Kamen Rider manga published in 1971, which contains a chapter called The 13 Kamen Riders. However, only 10 official Kamen Riders (discounting the artificial Alternatives) were featured in the TV series. Femme, Ryuga and Verde appeared exclusively in the movie Episode: Final and/or the TV special 13 Riders. Despite this the Kamen Riders revive later on and fight together against other enemies, even if their personalities would never allow them to do so within their own series.