|This article is about a/an faction in Kamen Rider Gaim and Kamen Rider Wizard.|
The OOO Army (オーズ軍 Ōzu Gun) is one of the warring factions in the World of the Sengoku Period, led by its lord, Nobunaga, who resembles the Secondary Rider ally of the prime Kamen Rider OOO, Akira Date (Kamen Rider Birth), with his attendant Ranmaru, and represented by its Bujin, Kamen Rider Bujin OOO. Nobunaga was killed by Kamen Rider Bujin Gaim after HON-NOHJI castle that he lodged in was set on fire. When Nobunaga and Bujin OOO fell to the hands of Kamen Rider Bujin Gaim, Ranmaru made Kaito the new lord of the OOO Army and being a Bujin himself. The army was renamed the Baron Army after Kaito became its lord.