How much is needed for a man to break? Kai was about to find out the answer to that question…

Kai Smith was an ordinary guy with a somewhat bright and hopeful personality. No matter what he faced, he faced it without letting the situation get the better of him. Until in an unfortunate sequence of events, he lost his parents, his home, and his chance to keep studying in a good college, and his girlfriend dumped him since he became a nobody.

He endured all that until the end, and then he cursed it all and wished for the end of the world, and then the end came, but people would have the chance to fight against the end, with the power of the class runes. Kai also obtained that power and decided to use it to do whatever he wanted, and no one will be able to stop him. Here start of the rise of the Dark Slayer.