King's Favor

Five hundred years ago, a virus invaded the Emperor Yuan planet. Disease and infected monsters once brought humanity on the planet to the brink of extinction. In times of crisis, mutants saved mankind, and humans also respected them as kings and vowed to remember the king's favor as long as they were born as humans. Now, with the advent of a new virus, where will humanity go? Can they still keep their vows, or will they be drawn into a darker abyss?