Marg was deprived his little brother, Mars, by Zure, and lost his parents. Therefore, he was living alone on the planet, Gishin. He became a member of guerrilla to riot against the dictator Zure, and he fell in love with Ruru, the daughter of the leader, Ura. However, the organization was destroyed. He was trapped by Zure, and he was brainwashed to become a soldier. Then, his long cherished wish that he would meet his brother again was realized… as a duel with him. Gaia, God Mars, and the Gishin robot Zeron receive redesigns although the OVA mostly focuses on an alternate telling of Marg's life on Gishin up until the events of episode 19. (Source: AnimeNfo)

It is 2911 and the solar system is made up of of 50 planets. I.C Blues, a gambler, makes a bet with the boss of a criminal syndicate known as Bloody God that it is possible to navigate the whole solar system in one year. Helping out Blues is J9-III, made up of Rock, Beat, and Birdy. To clear any obstcles, they have the transforming train-robot Sasuraiger. But the Bloody Syndicate will do anything to ensure the Blues loses the bet. (Source: ANN)

The Doron Empire from the Ganymede System discovered Earth as an ideal world for them to conquer. The interest of expanding the empire came as a result of the power-hungry General Ozmel who overthrew the current reigning Queen Medusa of the Ganymede System as a start of their universal conquest. Almost completely succumbed to the empire, Earth is at its last days, and one scientist, Dr. Shikishima, had only one hope in restoring Earth from its alien conquerors--- a massive mecha known as the Mechander Robo, specially programmed and designed to battle these invading aliens from complete takeover of Earth. Along with this awesome fighter machine, Dr. Shikishima also recruited three pilots to be placed behind the Mechander Robo's controls--- the mysterious Jimmy Orion, the scientist's son Ryosuke Shikishima, and Kojiro Hachijima. Although the primary storyline is Earth battling the Doron Empire, there is something within lead pilot Jimmy Orion's past that was somewhat connected towards the entire storyline.

In 2038, Yuuma Sawatari is an elementary school kid who loves everything about space and astronomy. He was initially excited when his parents bought a robot called Nanako, but he was disappointed when he learned that she was basically just a boring housekeeping robot. However, when he does finally try to talk to her about space, something strange happens. Her system crashes and is taken over by what claims to be a marooned alien ship! The alien ship wants Yuuma's help to get back to space! (Source: MangaHelpers)