The Celestial Realm is one of the three worlds that exist in the game. It's the home of angels such as Simeon and Luke, and the former home of the demon brothers prior to their fall from grace following the Great Celestial War.
Little is known about the realm but Luke stated that it was constantly daylight all the time (even during the night), which is the polar opposite of Devildom where it is dark all the time.
It's currently unknown who rules over the realm.
There are several types of angels mentioned in the series:
- Seraphim: angels with six wings and the highest ranking in the Celestial Realm. Lucifer was formally a Seraphim. Simeon was also a Seraphim before the Great Celestial War.
- Cherubim: a high-ranking angel that is known as a guardian. Beelzebub was formally a Cherubim.
- Throne: a high-ranking angel. Mammon was formally a Throne and was recommended the position by Lucifer. Little is known about them, but Mammon was Lucifer's assistant.
- Dominion: a type of angel that watches over the Human World according to Simeon.
- Principality: a type of angel mentioned by Mammon when teasing Luke.
- Archangel: an angel that serve as warriors, according to Luke. However, Michael is commonly referred as an Archangel despite his high ranking. Mammon was also an Archangel before being promoted to Throne. Simeon is currently an Archangel.