One Piece: Fist of the World - Chapter 10: Trafalgar Law

Medieval times, warring knights, dragons, demons, gods, pirates, behemoths...Barbaric, ignorant, backward, numb, starvation widespread, people unable to make a living...Damn it! Punch to explode this era!!Reclaiming wilderness, farming, bridge building, road paving, coal mining, excavating minerals!Leveling up, recruiting apostles, forging an army!Barrage troops! Pushing horizontally!Quack! My steel torrent is invincible in this world!!Roman: “I am your destiny! Kneel before me!”So, you were supposed to farm, but somehow you ended up establishing a vast empire and becoming the emperor?

“For those who dare call themselves gods, I, Wen Ran, will crush their legacy beneath my feet. Even dogs are more honorable than those filthy bastards!”A feared Godslayer, who, due to betrayal, perished under the might of the heavens, having his world destroyed. Saved by a mysterious system, Wen Ran was granted a second chance at life but reincarnated in the body of a lowly slave. Hunted by the gods who sought his head, Wen Ran vowed to reclaim his title by showing heaven his vengeance as a 'God Slayer.'

Liu Qing resigned.

He wrote on the reasons for his resignation:

“I’m going to inherit hundreds of millions of properties.”

- Description from novelbuddy

He was promised a world of magic, dragons, and swords.What he got was a hijacked system, and a realm ruled by cultivators who crush mountains with a punch.