In the 1800s, instances of unknown creatures— “demons” and “monsters”—were reported by the general public to the government. Officials brushed the sightings off as false reports. 

In 1906, in response to the bloody Battle at Han in 1858 against creatures where Korea’s army was no match, the government created the Academy of Legends with the help of a large, but secret, group of individuals who were more than just human, and had been fighting against such creatures for a millennium already. The Academy became known to the public as a rich, highly privileged boarding school that only a select few could be admitted into. 

In 1962, the true intent of the Academy was into the light when a couple of students were seen battling one such creature—a supernatural. They were dubbed the “guardians” of life, since a young girl was saved, and have been called “Guardians” ever since. In this time, they were idolized and praised. 

In 1992, the Guardians of Legends, now referring to a team put together by the Academy, became obscene due to an unknown incident. The Academy once again went under the cover of being a highly privileged, if slightly old-fashioned, boarding school. The public, along with newer generations, forgot that Guardians ever existed, and sightings of “demons” and “monsters” were quietly taken care of through newly-established teams of Hunters and Watchers, along with Guardians. The Academy decided to uphold a code of secrecy in which the public would remain oblivious to the world of the supernatural, and the Academy, government, and others, would remain mum. Those who tried to break the silence would quietly be taken away, never to be seen again. 

In 2000, Guardians, Hunters, and Watchers of the Academy banded together to form elite teams that carried out assignments issued by both the Academy and the government, while still keeping their individual roles. A Guardian was someone with supernatural abilities in which advanced physical capabilities were unneeded. Hunters were individuals with supernatural abilities that required significantly greater physical capabilities, and had so. Watchers were individuals who were more suited to aid Guardians and Hunters, but were not in any way weak. These teams excelled in their jobs and, together, effectively kept the peace between the supernatural and human world. They became known as the new generations of Legends within the supernatural world.

In 2008, the youngest team of seven Guardians, Hunters, and Watchers were put together. All were current students of the Academy, and considered prodigies. This team moved forward in ways the Headmaster of the Academy never expected and due to their success, he decided to put forth another team consisting of similar young, bright individuals.

The first team had been codenamed Exo-K. The second became known as Exo-M. When the two teams collaborated for an assignment, they were simply called Exo.

The government took notice of Exo-K and Exo-M, and decided to put the teams’ young ages to good use. To curb the amount of corruption the new generations seemed to be exposed to, they sent both teams undercover in regular society. The members would attend school, while keeping their true identities a secret, and at the same time carry out their usual duties. They would be overseen by an advisor, an accomplished Watcher, who would also act as their legal parent.

And thus, this begins their story.