Tetsuya Tsurugi pilots Great Mazinger in "Grendizer - Getter Robo G - Great Mazinger Kessen! Daikaijuu," joining a coordinated defense against Dragonsaurus. This massive prehistoric sea creature threatens Tokyo, prompting Great Mazinger's deployment alongside Grendizer and Getter Robo G to counter the global threat. During combat, Boss Borot is swallowed by Dragonsaurus. Tetsuya maneuvers Great Mazinger to wound the creature, facilitating Boss Borot's escape. This action weakens Dragonsaurus before its destruction. Tetsuya operates Great Mazinger's systems and weapons during the counterattack, consistent with his expertise as a combat pilot.