In the year 1999, humanity begins to advance beyond the solar system. The leader of the planet Gishin, Emperor Zule, aims to conquer the galaxy and ends up in a conflict with Earth as a result. In an act aimed to eliminate the Earth, he sends a baby named Mars to live among humanity. Mars is accompanied by Gaia, a giant robot that utilizes a new power source strong enough to destroy an entire planet. Once Mars grows up, he will destroy the Earth by activating the bomb within Gaia. However, upon arriving on Earth, Mars is adopted into a Japanese family and given the name Takeru. Seventeen years later, Takeru has grown a love for humanity and he refuses to detonate the bomb as ordered by Zule. However, the bomb within Gaia is set to explode if Takeru were ever to die, which would ultimately result in the Earth's destruction.

Takeru possesses psychic powers (ESP) and decides to join the Earth defense forces and becomes a member of the Crasher Squad (an elite space defense force) where he and his friends take a stand against the Gishin attack.

Unknown to the Gishin, five other robots were created in secrecy along side Gaia by Takeru's father and sent with Gaia to protect Takeru. The five other robots are Sphinx, Uranus, Titan, Shin and Ra. Whenever Earth is in danger, Takeru is able to summon the five other robots to combine with Gaia form the giant robot Godmars.