The Kikaika (literally mechanization) Empire invades our solar system, and in a matter of moments they take over and convert Neptune, Uranus, Saturn, Jupiter, and Mars, and set their sights on Earth. However, one thing stands in their way. Earth's ancient protector and soldier of light, Eldran. To fight this menace he gifts a 5th-grade class with 3 huge robotic dinosaurs, with the power to merge and form the giant robot Go-Saurer, which they then can pilot and use to stop the Kikaika Empire's advances.
Three boys, Kotaro, a ninja in training, Rikiya, a training baseball player and Yosuke, a studiying scholar were living normal lives in Aozora Village. One day, Kotaro along with his father Tobe accidentally broke the seal that links the Underworld from the Human World. Until Eldran, the warrior of light, appeared in front of Kotaro, Rikiya and Yosuke along with three strange machines. They were appointed to save the world from destruction as the Ganba Team and use the robot Ganbaruger. After their first victory againts the demons, Yaminorius put a curse on Kotaro's dad, turning him into a dog. He did the same to the three boys but it didn't work. Except if Kotaro, Rikiya and Yosuke revealed their identities, they will turn into dogs. Now, the three of them needs to save the world from the Underworld at the same time, keeping their identities as the Ganba Team low.
Elementary school children take control of giant robots to save the earth from the evil Jaku Empire.
This OVA is a sequel to the TV Series 'Matchless Raijin-Oh' consisting of 3 episodes.