AntiMagic Academy “The 35th Test Platoon” - Volume 3, Chapter 1 - Traitor

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…

This world is Heaven.

Because this world has everything you dream of, everything you wish for.

This world is Hell.

Because everyone in this world are parts of a never-ending massacre.

Are you fighting to survive, or fighting to come home?

- Description from Novelupdates

Being sucked into a fantasy world that nobody leaves doesn't sound half bad to Cain. He was a high school dropout with a drinking problem, living off disability due to his poor health, so it's not like he had much to lose except a few faithful friends he didn't talk to enough.

After a long night of drinking, Cain wakes up looking at what he believes to be the character creation screen of one of his beloved virtual reality games, but with no recollection of having purchased it. His unwitting choice to use the Random Character Creation option, unaware that the choice would be irreversible, sends him into this new world as a Puppet Master, a Summoning based class nobody else in the starting zone has ever heard of.

But as he soon realizes, this is no game, him and hundreds of others have been brought to another world with no instructions, no clear goals and no way home. It's a second chance to live a good life, but what will Cain be able to make of it?

A young man with no spiritual roots. A person who is thought of as trash by others. He constantly acquires various items thought of as waste by the cultivation world. No matter if it is garbage pills or useless materials, he will take them all!

- Description from Novelupdates