Upgrade System In The Undead Skeleton

In a world where there is no technology and there are ferocious beasts that prey on humans.

Humans also become strong to fight the beasts to survive.

There is a lonely child who wants to become a warrior to survive and get out of poverty.

However...

Plans don't match reality, he dies when he's dealing with a beast that's stronger than himself.

And when he was about to die, a notification popped up.

After that his world began to change...