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".

Sun Goddess of the Solari, Leona came to Earth in 2014. The genetics of God hidden on Earth has started to awaken. The first few awakenings include the Power of the Galaxy and God of War. An invasion by the alien Tao Tie, just to entertain Death God Karthus, are on the way to Earth. The Angels, the Devils and God seminary groups that have been monitoring the genetics of God on Earth make their moves. The God Seminary assembled the scattered warriors across Earth who carry the genetics of God to form the Black Troops. Radiant Dawn, Leona, lead the team and train them combat techniques to fight against the invasion. Morgana, the Fallen Angel came to Earth to sow the seed of darkness and plot to destroy the Holy Kayle. Angel Yan was send to Earth, informing the invasion of Styx galaxy by Tao Tie. Earth has just become the battlefield for the war of different civilizations. As the disasters continue, the Black Troops will realize they are fighting more than what they are asked for.

The story revolves around Kibayashi, a teacher whose hobby is speaking with the dead and whose special talent is exorcism. She seems to know everything about the other world, yet nothing about our own. (Source: AniDB)

It is the dark century and the people are suffering under the rule of the devil, Vandel, who is able to manipulate monsters. The Vandel Busters are a group of people who hunt these devils, and among them, the Zenon Squad is known to be the strongest busters on the continent. A young boy, Beet, dreams of joining the Zenon Squad. However, one day, as a result of Beet's fault, the Zenon squad was defeated by the devil, Beltose. The five dying busters sacrificed their life power into their five weapons, Saiga. After giving their weapons to Beet, they passed away. Years have passed since then and the young Vandel Buster, Beet, begins his adventure to carry out the Zenon Squad's will to put an end to the dark century.