Cha Eun works a regular 9-5 job as a janitor for the local train station, working tirelessly day in day out to merely scrap by living in his small one bedroom apartment. Although small, he lives far away from outside the walls, where mysterious creatures and monsters lurk. Occasionally, monsters find ways to enter the city, causing destruction and being the leading cause of death for the population. However, specially trained humans named 'Hunters' are employed to take care of monsters inside and outside the walls, in exchange of money for the rare materials these monsters are made out of. Cha Eun is like every other guy in their mid twenties, broke and dreams of becoming a hunter. To save others? Hell no! Becoming rich is the main objective, helping others merely come as a byproduct of the job. The only way to secure your chances of ever becoming a Hunter is to unlock your [Skill Card] by the age of 25, when your brain stops developing and can no longer have the capacity in their system to house an entirely new power. However, to be blessed with a [Skill Card], one must 'Impress' the system to prove you are truly worthy of possessing such immense power.