The Misfit of Demon King Academy (WN) - Chapter 0: Prologue

Sold by her own grandmother to become a shared wife to the poverty-stricken Ye brothers for twenty taels of silver, Liu Duo, unwilling to succumb to her fate, escaped in the night. She slipped and fell and died an inexplicable death.

Through a mysterious portal, Chen Jin arrived at this strange place – a post-apocalyptic world where civilization had been destroyed.

Consequently, he found –

A piece of metal scrap
A robot trash collector
A battleground
A city
A ton and more of gold
A copy of high-tech documents
A…
In short, Chen Jin found a planet.

- Description from Novelupdates

I was proposed to by the Final Boss.

What’s not to love about my new life after transmigrating into a Pet-centered world?
There are mighty creatures that come in all shapes and sizes. They can either be cuddly companions, helpers in your daily life, daring scouts or strong fighters. Or all of the above. Not bad, huh?

I have a family, but the fact is completely overshadowed by my younger sister. She thoroughly hates my guts, and she makes sure that I know this. Every. Single. Day.
Did I mention that she’s disgustingly talented while I am a bottom feeder? A terribly handsome one at that.

I have free rein to run the family business on my own. A small and quaint Pet Store. It should have been great if not for the fact that the previous owner of this body was born with ZERO affinity to handle Astral Pets…

It wouldn’t be a proper transmigration without a gimmick or a system to pave my road to greatness, don’t you think? I have one, but I don’t know if I would be better off without it…