The Promised Neverland

The Promised Neverland Summary:

At Grace Field House, life couldn't be better for the orphans! Though they have no parents, together with the other kids and a kind "Mama" who cares for them, they form one big, happy family. No child is ever overlooked, especially since they are all adopted by the age of 12. Their daily lives involve rigorous tests, but afterwards, they are allowed to play outside. 

There is only one rule they must obey: do not leave the orphanage. But one day, two top-scoring orphans, Emma and Norman, venture past the gate and unearth the horrifying reality behind their entire existence: they are all livestock, and their orphanage is a farm to cultivate food for a mysterious race of demons. With only a few months left to pull off an escape plan, the children must somehow change their predetermined fate.