World

Fujimoto describing Assiah and Gehenna as mirror worlds

The World of Ao no Exorcist is the main setting of the series. While the series is set in modern times, the story places our world next to a parallel world: Assiah, the human world, is connected to Gehenna, the Demon world.

Assiah

Assiah (物質界 (アッシャー)  Asshā) is the material world in which humans live. Demons can pass into this world by possessing anything that exists within it. It is the ultimate goal of Satan, the ruler of Gehenna, to make Assiah his own. Specially-trained humans in the world of Assiah can exorcise Demons back to Gehenna through various methods. Any kind of contact between the two worlds is normally impossible, except for Demons who live in Assiah by possessing objects.

Gehenna

Gehenna (虚無界 (ゲヘナ)  Gehena) is the world in which Demons live. Satan is the god of Demons and the ruler of Gehenna. Currently, not much is known about Gehenna. It has been stated that there is no material present in Gehenna. It is said that the only direct way to the Demon world is through the Gehenna Gate which only Satan can open. Gehenna first appeared in Chapter 119.

Rin destroying Gehenna gate

Gehenna Gate

A floating Gehenna Gate

Trivia

• The demon world Gehenna is likely based on Gehenna from the Hebrew Bible. Gehenna or Gehinnom (lit. Valley of Ben-Hinnom) in Hebrew was originally a desolate valley outside of Jerusalem where children were sacrificed to the false god Moloch by fire. By the time of Jesus Christ, it was used as a garbage dump where the fires burned continuously. Due to its unclean nature, the valley’s name came to denote the metaphysical place where God punishes the wicked for their sins for all eternity.
  • Gehenna is also seen as the Seventh Hell in Jewish tradition whilst it is believed to be the First Hell in Muslim tradition.