It was originally a very romantic day, but who knew that the end of the world was coming so unexpectedly. Originally they were just a few ordinary teenagers, but due to a mutation in their bodies, they were given the important task of saving the world. The ignorant teenagers embarked on a journey to save the world without knowing the future. By the way, a mysterious person suddenly pointed out that there was an undercover among them, and was this undercover preventing them from saving the world? ! As a result, the confused teenagers became even more confused and fell into a strange cycle of fighting monsters → leveling up → searching for undercover agents every day → continuing to fight monsters... This kind of cycle.
Finally one day, the undercover agent was found...