Daemon Realm

The Daemon Realm (悪魔界), also known as Hell (地獄), Netherworld (冥界) or the World of Darkness (闇の世界), is a Spiritual World where Daemons come into existence and the Domain of Demonic (魔の領域).

It can only be accessed through Hell Gates (地獄門), also known as Underworld Gates (冥界門). The Daemon Realm is also said to be a Parallel World (並行世界) of the Otherworld.