Story
In 2047, the metallic ore Gaimetal was discovered in a mythical layer 50,000m below the earth's surface.

Gaimetal is a high-purity energy source metal, and for some time after this new energy resource was discovered, it was mined all over the world.

However, in the year 2055, a metallic life form called 'Gaist' whose entire body was covered with Gaimetal, appeared and began to attack people.

In order to combat the threat of 'Gaist', humanity has established a supranational organization called 'Gaist Crusher Garrison' (commonly known as 'GCG'), which amasses the world's technological power to fight Gaist.

This is the beginning of the fierce and heated battle between 'Gaist' and humanity.