The Promise (Anime)

The Promise is an agreement between humans and demons made 1,000 years ago. The agreement was made to end a long war between humans and demons and states that the the world would be split into two worlds - the human world, where people live free from the threat of demons and the demon world, where human breeding farms were set up to provide food for the demons. The promise was made by Julius Ratri and "Him" and is upheld by the Ratri Clan.