Three years ago,
Humans have discovered evolution materials of beast with ability, this evolution material are used to help one awaken his ability.Through this evolution material Humans were able to gain ability, if one is lucky to find the evolution material of a strong beast he will be able to awaken a strong ability.
The Slavlords came to the earth to wage a war against human because of the fear that humans will be powerful than them.The war between the human and Slavlords was a very powerful war with no side winning. The Slavlords didn't have any ability but has a strong body which made the battle tough for humans.
The humans and Slavlords signed a treaty of peace .The humans didn't trusted the Slavlords, so they decided to make a military school for children of age 15 to train and make them a powerful warrior before another war with the Slavlords