In peacetime, the young boy Hongdu (played by Koji Seto), who inherited the mantle of Kamen Rider Kiva, entered Morira High School and started a bumpy campus life. One day, a fugitive in a panic broke into the high school. His name was Sugimura Takashi (played by Ken Horiuchi), a strange man who had not aged in 22 years. After a period of chaos, Sugimura Takashi was kidnapped by two weirdos who looked like Fangire. From the mouths of Kamen Rider Rey Shiromine Tento (played by Takuma Yamamoto) and Nago Keisuke (played by Keisuke Kato), it was learned that the secret of Sugimura's immortality was most likely related to the kidnapping of a female musician that he personally planned 22 years ago, and all this led to the resurrection of the most terrifying ancient demon king Legendora. In order to stop Legendora's conspiracy, Hongdu traveled through time and space back to 1986 and met his father Hong Yinye (played by Kohei Takeda). He and his father tried to change history, but everything was still heading towards the worst situation...