Akuyaku Reijou ni Nanka Narimasen. Watashi wa『Futsuu』no Koushaku Reijou desu! - Chapter 186.1: The truth about Wolfanea.

I accidentally changed the whole world, the resurrection of the dead, genetic variation, recovery of the qi, mountain and seas reborn, land and seas expanded and evil spirits have started to appear.

Ghosts are now commonplace. Some people now have three heads and six arms. Some people have obtained martial arts techniques and ordinary people are now just cannon fodder.

Fortunately, I have acquired an ability which can make various items mutate.

books into martial arts or cultivation manuals,

fruits into precious treasures of heaven and earth or poison that you can only imagine and…

weapons, that can split the earth or gain sentience!

- Description from Novelupdates

The demon Sang Jiuchi woke up from a seal and found that he was bound to the Quick Transmigration system, and the characters he took over were all without exception, the worst villains.

Blackmailing the top streamer but ended up killing his own despicable tech genius…

The vicious true young master who framed the fake young master but suffered the consequences…

The murderous master who humiliated his apprentice but was killed…

The sinister mermaid who seduced the general and was slaughtered…

The hypocritical pope who deceived people and was burned at the stake…

- Description from Novelupdates

This story is set during the end of the Sui Dynasty, a time where multiple powers struggled for supremacy and power.

Into the fray enters two orphans Kou Zhong and Xu Ziling; these two youths by many chances and luck obtain ‘The Secret to Long Life’ allowing the two to obtain profound martial abilities and a chance to rise to the top in this age of turmoil.

A Count’s Daughter who lost in the running to become the Second Prince’s fianceé, Camilla. The Prince chose a Baron’s daughter as his fianceé, and the world blessed the two’s love as fated. On the other hand, Camilla who was tailored and elevated as the love’s villain in the end, as punishment she was made to marry a terribly fat and ugly man――called『Toad of the Swamp』from his appearance, a lord of a remote region named Alois.