Seal (World)

The Seal (異界) or the Otherworld (異界), also known as the Underworld (冥界) is a Demi-Material World that overlaps with Spiritual Worlds such as the Elemental Realm and the Daemon Realm, in which the Spooky Palace is located and where Aggressors live.

The Otherworld is said to be a Parallel World of the Daemon Realm, and can also be accessed through "Underworld Gates".