It seems like everyone's fate is sealed by the universe. by the stars. Hyunjin was just a baby when he was left by the dumpster and a couple found the kid and deemed him a miricle. He was destined for greatness and that's what his adoptive parnets set out for him. Turns out this couple was elte trainers for a hidden team of slayers. 
hyunjin didn't have the normal childhood life like his peers. He was mainly isolated by his parnets that had trained him to the brink of him pushing his limits. hyunjin was raised on strict discipline and was taught if you wanted something you have to be rewarded for it. Gifts are for winners. And so everyday hyunjin pushed himself to be the apple of his parent's eye. 
Part of his final training, he was set out to do a misson with his parents. Capture a rouge vampire that terrized the human village. his parnets stood back as they watched their star child in combat with the blood er. Once slayen by himself, Parkha was initiated into the inner circle of slayers. 
By the age of 18, hyunjin worked alone on missons after proving himself that he worhy of such work. There are times were he was ordered to work in a team. which was his downfall when he turned 21.
21 wasn't a good year for him. the team he had been working with seemed incapable of actually winning battles. they were so sloppy that most would end up injured or half dead. the captain so one night the team got ambushed by demons. the team was killed and parkha was spared but was thrown into slavery.
he now wishes to escape being a slave so he can get back into his work and take revenge on his fallen teammates.