Kamen Rider OOO(仮面ライダーOOO(オーズ),Kamen Raidā Ōzu) is the main protagonist and one of the main characters in the series of Kamen Rider OOO. His title is pronounced similarly to both "Os," refers to the three O's in the series title which represent the character's transformation items, as well as meaning "multiple kings" (王ｓ, Ōzu). The three O's also represent the infinity symbol with an additional circle over the center, stating that Kamen Rider OOO is Over Infinity. His debut was a cameo in the film where he fights against the Luna Dopart. Before Eiji Hino, there was a Previous Kamen Rider OOO who had fought and sealed the Greeed away. Also Kamen Rider OOO is the 100th Kamen Rider to be created.