在这部无敌太空船科幻/动画片中,ガイラー星的考察队遭遇事故而在地球迫降，迟迟等不到本星救援队的考察队内部终于发生了内乱，过激派ゲルドン夺权称帝，建立ガイラー帝国并准备利用超兵器空爆机器人侵略地球。主和派的ヤン博士为了阻止ゲルドン的野心，将新型空爆机器人“グロイザーX”托付给女儿リタ，并让她将ゲルドン帝王的野心告知地球人。リタ脱出后遇到了特技飞行员海坂譲，两人一同驾驶グロイザーX开始了战斗。
The Gaira aliens, hidden in the Arctic, plan to conquer Earth. Captured and forced to work for the aliens, Dr. Yan creates the ultimate weapon, a transformable aerial robot called Groizer X. Groizer X was 100 meters tall and weighed 1200 tons. Entrusted to his daughter Rita, Groizer X escapes the clutches of the Gaira and lands in Japan, where pilot Joe Kaisaka meets a wounded Rita. Taking up the controls of Groizer X, Jo and Rita fight against the Gaira invasion.
