Elf Tensei Kara no Cheat Kenkoku-ki - Chapter 14Book 4: -3: Defensive Wall

Before going to college, an ordinary high school student went to celebrate and got drunk. When he woke up, he found himself in a completely different world. There was a big sect, the approaching sect entrance examination, a slum where his body’s previous owner lived, and a shared memory about a missing young girl.

When he got tangled in a fight with a few punks in this different world, he fell off a cliff and miraculously found himself still alive, with two more voices ringing inside his head. They were Sword Master and Saber Master. In the company of them, he continued to find out more about this whole new world. He took the sect entrance examination, entered the sect, met a strange man in black, and even participated in a major competition of the sect to have a chance to win over his peers!
In this whole new world, he was born again and got to explore the fantastic martial world!

- Description from Novelupdates

A mysterious teenager who had lost his past, awakened in Tianlong Continent. Mistaken as the Ye family’s Son, he used this identity to observe this chaotic world and to search for his past self, but only to find an inevitable and terrible fate, therefore he indignantly laughed at his destiny, and revealed his prowess to rule the lands under the heavens.

Alex is a young man who struggles to make a living in the world's biggest game (Ancient world). He works as a mercenary who does every job he can find. It's been five years since his suffering started.

Ancient World creation was only possible by the World's greatest invention, “AI ZERO.”

Ancient World A vast planet Multiple times the size of Earth Ruled by Great empires, Big organizations, and hidden Shadowy associations.

A Fantasy world filled with prehistoric animals that have gone extinct on Earth. The creatures humans have only heard of in fairy tales and old stories, Monsters beyond the imagination of humans, roam the vast lands of the “Ancient World.”

Everything was going well, but it all changed on that day.

When the United States told the World “AI ZERO.” and “Ancient World.” technology was a gift from a very advanced intergalactic civilization. That has surpassed humanity in any way of life by an uncountable margin.

Humanity entered a new era, and the Ancient World became humankind's most important part of life.

Alex joined the game to make a living and support his family, but things didn't go as he had hoped.

After suffering in the Ancient world, Alex returned five years back in time.

Alex knows that the Ancient World is not just a VR game.

Now with a new chance in life, Alex will get strong and reach the top while finding the truth about the Ancient World.