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)

Creatures known as Shokujinki have been secretly living alongside humans for hundreds of years. Though they may look like humans, Shokujinki are able to transform into uncontrollable beasts with gigantic claws and consume humans to survive. The equally secretive Kifuuken dojo specializes in killing Shokujinki by cutting off their arms, and is the only force preventing unchecked Shokujinki domination. Toshihiko Momota, the son of the leader of the Kifuuken, is instantly charmed by a mysterious woman named Yuka Kamitsuki. Their relationship is complicated, however, because unbeknownst to them both, Yuka is a Shokujinki and Toshihiko is sworn to kill her. Meanwhile, the Kifuuken is having a crisis of confidence as Toshihiko's brother Kazuma pushes against tradition and tries to modernize the Kifuuken. As emotions are strained and the secrets of both the past and present are revealed, who will live, and who will be eaten? [Written by MAL Rewrite]

A boy, Tsuwabaki Daiya found a black fire in an ocean when he and his father were in a small boat. A big monster came out of the fire, and the father and the crews were disappeared into the sea. When he was about to become the next victim, a large mecka dragon appeared and saved him. 5 years later since then, Daiya becomes a junior high school student. A big monster reappear, and he meets the mecha dragon,"Daiku Maryu". The head of the dragon separates from the body, and it turns into the body of a super robot, Gaiking. He gets in Gaiking, fights against the monster, and beats it. He learns that there is an enemy that plots to conquer the world, and he leaves for another world, Darius, to stop the plot. (Source: AnimeNfo)

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".