The children in the manga/anime series "The Promised Neverland" discover the true nature of Grace Field House by uncovering a dark secret - that they are being raised as livestock to be harvested by demons. They stumble upon this truth when one of the main characters, Emma, Norman, and Ray, start to notice inconsistencies and strange occurrences within the orphanage, leading them to investigate further and ultimately uncover the horrifying reality of their situation.
