On June 2, 2008, Toei announced on its various official websites that there would be a series of short five-minute internet movies that are spin-offs of both Kamen Rider Kiva: King of the Castle in the Demon World and Engine Sentai Go-Onger: Boom Boom! Bang Bang! GekijōBang!!Icon-crosswiki.png to be accessed by a mobile phone service. In the case of King of the Castle in the Demon World, the featurettes are called Kamen Rider Backwards-Kiva: Queen of the Castle in the Demon World, the first webisode released on July 11, 2008. In these shorts, Otoya and Yuri are brought into the present by Castle Doran when the mysterious Queen of the Legendorga is about to be revived. The shorts themselves are all zany misadventures of everyone in the Kiva cast. In the end, the Legendorga Queen is revealed to be Shizuka, however in the battle's climax, it is revealed that the entire event was only a dream. The Kiva net movies would become the first of a recent tradition as every future show in the Kamen Rider Series has since had a set of net movies for their respective summer films.