The Other Side/Rise of the Crow
https://www.webnovel.com/book/the-other-side-rise-of-the-crow_20563987806720905
For all of 15-year-old Crow's life, he's been at the mercy of an extremely cruel world.
Abandoned by his birth parents and eventually his foster parents, Crow has strived to live a "semi-normal" life.
After running away from his foster parents at the tender age of 12, Crow spends the next three years learning how to survive on his own.
On one fateful night, while trying to get some food from the meat market, Crow is chased down by the cops and narrowly escapes.
While looking at his haul on top of a construction site, the structure below him gives and Crow dies.
However, he soon awakens in a cave with strange clothing on, a triangle-shaped tattoo on his right arm, and a hazy memory.
As he walks down the cave he finds three other kids around his age with the same clothing on and the same tattoo.
“We need to find some answers! There are way too many coincidences, our tattoos, our clothes, the fact that all of us were sleeping in this cave. I think I see a little bit of light ahead of us. Let’s go!”