He was just a normal(?) scientist who developed a Zombie virus to take revenge on humanity but also saved humanity(?) who died after living his life till old age, When Su Lanyu opened his eyes again, he found himself inside a...very black and dirty novel. And he became a crazy bloodsucking devil Lord?

Su Lanyu: Scientists need more blood to work.

Later he found that he arrived 2 years before the start of the story, he had no interest in the story cause he was already in worry about the Demon realm. Devil Lord had a wife(?) and that wife had an affair with Devil Lord's subordinate.

Su Lanyu: I bless you but please be more secretive!

Then he was accused by some Demon elders of not having children and he found that no, he has children...Not one but two! They are Devil Lord's elder brother's children who died years ago leaving him these babies...

Su Lanyu: Ok I like children, I wanted to be a dad.

Then he had to help demons recruit children, then came the backward technology who Su Lanyu couldn't take, and decided to remodel the whole demon realm. Then a Demonic elder was sick, he had to take over his duties, no much later another problem topped, so on so forth. Su Lanyu was so busy that he forgot when the story started and suddenly he was told that the Righteous Sect Alliance Leader have decided to have a truce and for that, they will marry their beloved 'Daughter' to Su Lanyu, Su Lanyu who knew it was the Male Lead replied.

Su Lanyu: I got a wife who has affairs, two villainous children, 5 childish elders, 3 paranoid couples, 4 problematic subordinates, and a whole Demonic sect reconstruction, I don't want to handle the Male Lead, So sorry, I am out!

Male Lead: I must marry you and take revenge for my last life!

Female Lead: I want to see the gorgeous Demonic Sect! I Must come with my senior brother!

Father of FL: I am tired of living in a righteous way, let me accompany my daughter to experience a demonic way.

Villain: I suspect that my mother is in the Demonic sect, Must check!

Second Male lead: My crush wishes to see Demonic Sect, then I will protect her!

Cannon fodder Sect leader: What am I doing alone, let's go together.

Cannon Fodder Elder brother of Male Lead: My little brother is lovestruck! I will let him see the real face of Demonic Clan!

Third Male Lead: Why is everyone going to the Demonic sect? Take me too! Let's have fun together!

Su Lanyu and Demonic Sect:...We don't welcome you!!!