World-Saving is a Skill

For 20 years, Hyeonseok fought monsters in another world before finally managing to save it and be sent back to Earth as a reward. Now a former deliveryman named Chanseok, he looks forward to enjoying modern conveniences, only to discover that Earth is very different from what he remembers. Monsters have started appearing from Erosion Points that pop up at random, and people with innate abilities become Hunters to defeat them. Reluctantly, Chanseok applies to become a Hunter himself, mostly for the money. He saved the world once before, so how hard can it be the second time?