Cage Force(former name Demolition Octagon Gear (D.O.G.)) is a defunct Japanese Mixed Martial Arts (MMA) organization operated by Greatest Common Multiple (GCM) Communication. It was the first Japanese MMA organization to feature an octagon cage instead of a ring. Yushin Okami, Eiji Mitsuoka, Kuniyoshi Hironaka and Keita Nakamura experienced a cage match in D.O.G before contract with UFC. It enforced the Unified Rules of Mixed Martial Arts when the changed name to "Cage Force" from "D.O.G.", to prepare Japanese MMA fighters for the UFC. Cage Force tournament winner was entitled to a contract with UFC. Yoshiyuki Yoshida and Takeya Mizugaki have been contracted to the UFC and WEC by winning the tournament.