Side Character Transmigrations: The Final Boss is No Joke - Chapter 26

However, he did not know that he was not raising just a harmless pet, but a biological weapon secretly made by the government… a real monster.

As a former librarian, Rand felt that he had been living an ordinary life, the one that he had reclaimed unconsciously every single day.

Recently, he has been a little upset because the pet fish he accidently brought home to raised seems to have undergo some strange changes

Well, it turned into a merman.

- Description from Novelupdates

In the year 3021 of the Western calendar, the last world war broke out and the earth was destroyed.
A group of survivors left their homes to settle on new planets. New races, new classes are born. Cities began to be built, countries rose one after another, conflicts between different races intensified, and social order was re-established…
The transformation from a survivor to an aggressor was but a moment.
This is a world where the strong are respected and the fittest survive.
Shang Ping was reborn from the earth in the 21st century to this planet. The moment he woke up, his fate had already begun to change.

Content Labels: Strong Soul Conversion Court Marquis Heaven’s Chosen
Search keywords: Protagonist: Shang Ping ┃ Supporting roles: Solan Edrich, Liu Xi, Austin ┃ Others: future time and space, battleship, interstellar war, rebirth, distant starry sky

- Description from novelbuddy

Though he received the skills necessary to teleport across worlds, the king who performed the summoning ritual attempted to trick him into wearing a slavery collar, this annoyed him so he kidnapped the princess and returned to Earth.

Song Xi, the proprietress of the supermarket in the 21st century, wakes up and finds that she has come to a time when supplies are scarce and extremely difficult, and she has ‘married’ into a mountain valley where the conditions are extremely difficult.

Unexpectedly, the supermarket opened in a small town became her personal space, and the husband beside her was an excellent man who could hunt, fish and farm.

Song Xi felt that being a low-key rich man with a loving husband, two or three confidantes, endless fruits and vegetables, and living a small life was pretty good.

[Farming] + [Gourmet]