One Night Stand With My Ex's Billionaire Enemy - Chapter 87 Genial Host, Hostile Guest

After all, transmigrators of this era were no simple matter. Some became slimes, others turned into treasure chest monsters, and some were even reduced to mere skull--such things were all commonplace.It was nothing more than playing a villain, Shiayar didn't care. Wasn't it only natural to pay some price to become stronger?[Destined Great Villain System][“Let this world feel the agony!”][Newcomer Mission: Let the young and naive Grand Duke's daughter of the Azure Garden Dukedom, Miss Silvia, experience the betrayal of her loved ones and, amidst the pain and despair, complete her transformation and rebirth.]

He became the villain in the possessed game, the rival of the main character, and the second seat.

The end of the world is coming, the world has undergone great changes, and everything has changed. Plants, animals, and even insects, as long as there are living things, have mutated.
Become more powerful, and even evolved supernatural abilities, such as chickens and ducks that can fly to the sky, such as cats and dogs that can breathe fire.
But only humans, without any obvious changes, seem to have fallen from the top of the food chain to the bottom of the food chain overnight.
Any creature that can open its mouth to eat can treat humans as food.
But fortunately, this world has not completely killed humans. Gradually, humans discovered that they had the ability to cultivate compatibility with other creatures.
As long as it has a high degree of compatibility with some powerful mutant creatures, it can be used for its own use to achieve the purpose of protecting itself.
Fang He is a person who is very compatible with mutant animals, but it is also because of his ability that he has changed from the strongest to the stupidest.
Fang He, who was reborn, said, “Hmph, this time…”

- Description from novelbuddy

Step 1: Inherit a creepy old mansion.Step 2: Unlock a cursed system that makes girls fall dangerously in love with you… just by saying “hi.”Step 3: Learn that if you don’t reject them within 10 texts, something terrible happens.My name’s Ren.And apparently, I’m the “Catalyst for Affection-Based Catastrophes.”(Yeah. That’s literally what it said.)My peaceful new life? Over.Now I’m stuck in a house full of magically unstable girls:A sword-swinging elf.A fire mage with zero personal boundaries.A strict class rep who faints if I so much as look at her.And a witch who cursed the bathroom mirror to spy on me.They’re beautiful.They’re powerful.They’re dangerously obsessed.And if I mess this up, someone’s going to get hurt—maybe me.Reject them too late? Game over.Fall for one of them? Even worse.This isn’t a dating sim.It’s survival of the cutest.Welcome to my life. It's not just a harem. It's a hostage situation.