Extra's Guide to Surviving a Dark Fantasy World - Chapter 68: Expansion Initiative

It’s the beginning of the Apocalypse, and zombies are running rampant over the Earth.

“It was a book.It was a scripture.”Its cover was made of the skin of those who hold a grudge against humans.Its words were written with the blood of those who hold a grudge against heaven.Its weave was created from the sinews of those who hold a grudge against earth.The ancient demonic object, restraining darkness shaking heaven scripture (制暗震天經).Yeon Sang-hyeon, who signed a contract with the restraining darkness shaking heaven scripture at the last moment of his days, is now rewriting his own destiny.The peerless genius met the ancient demonic object!

Kaito Nakamura, a shy university nerd, thought he’d found love when the stunning Aiko chose him as her boyfriend. Their sweet, fluffy romance fills his lonely world with hope—until he discovers she’s cheating on him with multiple guys, reveling in the taboo thrill of betraying someone so innocent. Heartbroken and humiliated as explicit photos of her circulate online, Kaito’s tears are interrupted by a mysterious popup: the “Revenge NTR System Beta.” Promising retribution but with a chilling condition — he can’t break up with her.Contains Ntr, read at your own risk

With the revival of spiritual energy and the breakdown of the order of species, it is a difficult test whether human beings can still stand at the top of the biological chain.

(There is already an old book, The Strongest Descends in the City, you can read it.)

- Description from novelbuddy