Devils (悪魔 Akuma?)Edit
Devils are powerful beings that come from the Underworld. High-ranking Devils (known as Pure Devils) rule over other demons depending on their family's rank and prowess, and can have up to 15 "slaves", which are represented by each piece in a chess game (Rook, Knight, Pawn, etc.). Lower-ranking Devils are often looked down upon, and usually serve a Devil of higher authority. If a Devil were to divert away from his/her master (then on known as a "Stray Devil" (はぐれ悪魔 Hagure Akuma?)), they have to be killed before they go out of control. The ranks of the Devils are spilt into Low-Class Devils (下級悪魔 Kakyū Akuma?), Middle-Class Devils (中級悪魔 Chūkyū Akuma?), High-Class Devils (上級悪魔 Jōkyū Akuma?), and Ultimate-Class Devils (最上級悪魔 Saijōkyū Akuma?).
(四大魔王 Yondai MaŌ?, lit. "Four Satans") The Four Maous that lead the Devils. The current Maous are not the original ones, rather they inherited their names. Therefore the names "Lucifer" and "Beelzebub" are not personal names, but are more like managerial positions.
(72柱, 元72柱 Nanajūni Hashira?, referring to the 72 demons of the Ars Goetia) The 72 families of pure-blooded Devils. The families representing the 72 Pillars are: Bael, Agares, Vassago, Samigina, Barbas, Valefor, Amon, Barbatos, Paimon, Buer, Gusion, Sitri, Beleth, Leraje, Eligos, Zepar, Botis, Bathin, Sallos, Purson, Marax, Ipos, Aim, Naberius, Glaysa-Labolas, Bune, Ronové, Berith, Astaroth, Forneus, Foras, Asmoday, Gäap, Furfur, Marchosias, Stolas, Phoenix, Halphas, Malphas, Raum, Focalor, Wepal, Sabnock, Shax, Viné, Bifrons, Vual, Häagenti, Crocell, Furcas, Balam, Alloces, Caim, Murmur, Orobas, Gremory, Ose, Amy, Orias, Vapula, Zagan, Valac, Andras, Haures, Andrealphus, Cimeies, Amdusias, Belia, Decarabia, Seere, Dantalion and Andromalius. Out of the 72, only 34 are still active after the war.
(番外の悪魔（エキストラ・デーモン） Ekisutora Dēmon?, lit. Devil of Extra) Houses of Top-class Devils who are not part of the 72 Pillars which consist of pure-blooded Devils. Currently the only houses known are the House of Lucifuge, the House of Abaddon and the House of Belphegor.