|This article is about a/an organization in Kamen Rider Fourze.|
The Over Space Technology Organization (外宇宙技術開発機構 Gai Uchū Gijutsu Kaihatsu Kikō) or OSTO (オスト Osuto) for short, is a science organization that created a lot of cutting-edge (if unusual) technology through Cosmic Energy. One of their most usually seen products are the Astro and Zodiarts Switches, and the equipment of Kamen Rider Fourze.
A space station owned by OSTO was on the moon until it was destroyed in an explosion with the Zodiarts Switches stolen by a man with glowing red eyes, with the Rabbit Hatch being all that remained of the original station. That man would later become the maker of Kamen Rider Meteor's equipment.
After the disaster, OSTO was supposedly remade into OSTO Legacy, and later make themselves known to the Kamen Rider Club's Kengo Utahoshi, inheritor of the Rabbit Hutch, when the Alicia Federation began their attack on humanity. However, it turned out that OSTO had dissolved after the space station's destruction, with OSTO Legacy being a front to the true villains of this incident.
Eventually, all hints of OSTO's greatness were wiped away with the deaths of Kuniteru Emoto and Mitsuaki Gamou, as well as the destruction of the Rabbit Hatch, with only a now human Core Child Kengo Utahoshi being what's left of OSTO's legacy.