[No System + urban superpowers + invasion by other races + one female lead (no female lead?)]
After a strange celestial phenomenon, demons descend upon the human world. An unusual demon takes up residence inside the protagonist, and the two strike a mutually beneficial deal.
One man and one demon: he wants to kill demons, while it wants to eat them. Working together, the protagonist rises to the very peak.
Enter the demon race, slay the Demon King. Who dares call themselves king beneath heaven and earth!
