Re:Zero Kara Hajimeru Isekai Seikatsu - Chapter 44Arc 7, - “Shrinking Vision”

Spicy Fabre, a YouTuber specializing in poisonous insects and venomous creatures is reincarnated in a Murim. The Tang Family of Sacheon wants him.

The simulation is over, and the entry is obtained: a showdown!

Looking at this entry, Zhao Meng was stunned.

“How should this term be used?”

“Hey! Here’s a wounded fox!”

…

A few years later, a woman who looked like a fairy appeared in front of him, and said:

“My lord, I’m here to repay my favor!”

This book is also called “Starting from Transforming Monsters”

- Description from novelbuddy

I am the sword.
Killing a man amidst a thousand miles, no one dares take ten steps.
Killing a man amidst a thousand miles, no one can take ten steps.
Killing a man amidst a thousand miles, ten steps? Not possible!
I am the sword, the sword is me,
On the path towards heaven, each shall wield their own.

The Immortal Path led to Longevity and Sovereign was heading in ease. When the Longevity was no longer in ease, all living beings were just prisoners. Conspiracy, internal strife, and the invasion of the others, all of it emerged together. 

In such a world, there was such a young man. He made his way upstream, stepping on blood, defying the emperor, destroying the various kings, and slaughtering his way through the hundred clans to form an Immortal Path towards the throne of Sovereign! The Immortal Path was endless, while the Sovereign was limited. He used his blood to forge his immortal legend.

- Description from Novelupdates