One day a portal to an unknown world, a gate, opened. From it came monsters who attacked and tried to take the land of the residing humans.

The king sent his best warriors to slay the monsters. They suceeded but soon found themselves facing a second and third gate. In response the king created a new order of knights whose sole purpose would be the hunting of monsters and subsequent closing of the gates they came from, the Gate-Keepers. A school was then created with the purpose of training these new knights and researching the monsters and gates they would be battling. They would also research and teach those with an aptitude for a new power known as magic, a power that became known of only after the appearance of gates.

A short time after the first appearance of the gates is where the story begins. Artame, a village commoner, loses his home to a gate and finds himself lured into the Royal Keeper's Academy where he will have to face challenges he never expected in order to become stronger and realize his desires. Nobility, monsters, and hidden beings are a few of the harsh realities that await Artame.