Youthful Transformation (青・春・変・身 Sei・Shun・Hen・Shin) is the first episode of Kamen Rider Fourze, introducing the series' setting and the initial main cast following the of Gentaro Kisaragi and Yuki Jojima in Kamen Rider OOO Wonderful: The Shogun and the 21 Core Medals and Yuki and Kengo Utahoshi in the finale of OOO. It is the first part of the initial Orion arc.