: The series is known for its intense "battle of wits," utilizing psychological pressure and horror elements rather than direct physical combat. Key Characters
: A cynical and highly intelligent boy who has known the truth of the orphanage for years and acted as a double agent.
: The story eventually reveals a world split between humans and demons due to an ancient "Promise". The children's struggle shifts from a simple escape to a grand battle for the freedom of all "cattle children".
: The optimistic and athletic protagonist who is determined to save every child, regardless of the difficulty.