Following her grandfather's recent death, Hamaji Ooyama lives out her days on an isolated mountain hunting for food and caring for herself. One day, Hamaji's brother, an aspiring samurai living in Edo, sends her an invitational letter to end her solitary life and join him in the city. When she arrives, however, she is met with a grisly sight—the heads of six dogs displayed for all to see. These heads belong to the Fuse, a group of eight human-dog hybrids that have been terrorizing the people of Edo. Hamaji assists a strange man escape a group of assailants and makes it to her brother's house, where he asks that she help him collect the heads of the remaining two Fuse, as well as the Shogunate-sponsored bounty. But it is easier said than done—as the Fuse can blend into human society almost seamlessly—and the kind man Hamaji had just helped showed the Fuse's telltale signs.

In the year 2047, mankind discovered a rare metal ore called Gaimetal, which possessed a huge amount of energy, and mining for these strange metal ore begins all over the world. However, in 2075, humankind were been constantly attacked by Gaist, a race of metallic creatures whose bodies were encrusted with Gaimetal, thus forming the GCG (also known as Gaist Crusher Garrison), an organization tasked with dealing against the Gaist. In 2064, the GCG send out mankind's line of defense: the Gaist Crushers, humans who can wear a special Gaimetal armor called Gaist Gear, and battle the Gaist,as well as the threat opposed by a mysterious organization called Erasers. (Source: Wikipedia)

Fujita Reiji is the owner of an art gallery, Gallery Fake. He deals with fake items, and is also familiar with the black market. However, he has a special talent for art, and used to work for the Metropolitan Museum of Art in New York as a curator. (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.