The Romance Of Mr. Walton - Chapter 70

Our straight (?) bottom woke up ten years into the future and found himself on the bed of his childhood friend… At the start, the bottom was shocked to his very bones, but he soon quickly accepted this premise and found the whole situation to be rather amusing. Precisely then, the bottom once again went back to his timeline — back to when he and the top were just platonic childhood friends.

Landmines include but are not limited to: Sweet & naive bottom, a president story, logic is dead, slow-progressing romance, the protagonist’s name has too many character strokes, the names are hard to pronounce, too many gay characters…

- Description from novelupdates

In a modern world where cultivators need a place to cultivate or vent their boredom, there are private businesses that set up instance dungeons with the aid of technology and cultivation magic to enable cultivators to train and commoners to experience the life of cultivation. They are called dungeon suppliers.
Xie Jin's one and only dream was to be a dungeon supplier and when his only relative passed away, the relative's inheritance gave him a plot of land and surprisingly, a 'System' Module which the relative had previously used.
With the help of the system, Xie Jin decided to pursue his dream of becoming the number one dungeon supplier.

mc gets transmigrated to Fallout New Vegas with the merchant system. let the questionable adventure begin.

When he woke up, Rono traveled to the world of pirates.

I thought I could live happily and peacefully.

But the appearance of Tianlong people broke this situation!

Rono, watching his parents being shot to death by Tianlong people!

Under extreme anger, Rono awakened the system and vowed to kill all the Tianlong people!

From then on, a [Extremely Evil One] who specialized in hunting Tianlong people was born!

Wherever Rono went, the Tianlong people shivered!

Admiral?

Two more and I will kill all of you rubbish!

Karp: The Evil One?

He is a monster created by the Tianlong people, and one day the Tianlong people will pay for it!

Roger: 【One Piece】?

Compared with [The Evil One], it’s nothing but a cloud!

Whitebeard: [The strongest man in the world]?

No, no, Rono is the strongest!

Rocks: In terms of killing Tianlong people, Rono is the first, I am second, everyone else is garbage!

- Description from novelbuddy