『Belphegor』

There are eight layers to the Devildom, and as mentioned during the normal story mode, The Demon King — Lord Diavolo's father — lies willingly dormant at the very bottom. Due to this, Lord Diavolo rules as the de facto king of the Devildom.

In the Devildom, there is no sunlight. The world exists in a constant state of darkness at all times, though according to Diavolo there are different degrees of darkness depending on the time. Despite this, demons still adhere to a "day/night" schedule where they sleep and are expected to awaken in the "morning" as evidenced by the fact that the demon brothers often sit down together for breakfast and dinner, as well as go to sleep and attend school/work at specific times.

The sky and its constellations are different from the human world's. In the Star-Crossed Lovers Devilgram, an autumn sky constellation is mentioned — the Pool of the Abyss — along with the myth associated with it. One star represents a beast, and another the maiden that was carried off by it. The nebula below the two stars symbolizes the pool created by her tears as she yearned to see her beloved. In Nightbringer Lesson 60-2, it is mentioned that the Devildom's moon contains more magic than the magic in all of the lands of the Devildom combined.

In Lesson 47-9, Belphegor mentions "Devildom script", meaning the Devildom likely has their own language.

It is stated in Season 3 that the Devildom once went to war with the Celestial Realm. It is unclear what the outcome of this war was, but this war ended long before the Great Celestial War.

In Nightbringer Lesson 58-5, it's mentioned that demons have cells that are homogenous and that these cells can't mix with any other type of cell.

The Royal Academy of Diavolo (commonly known as RAD) is a school for demons in the Devildom.

Diavolo says that the purpose of the school is that the population of the Devildom is given an adequate education in order to have a healthy and well-ordered society. According to the Devilgram The Glory Days, RAD was already in existence when Lucifer and his brothers were still angels.

Belphegor was "born" in the Celestial Realm as an angel along with his brothers and younger sister, Lilith. He, Beelzebub, and Lilith were all very close. He had loved humans and was always sneaking down to the human world, which led Lilith to become interested as well.

After Lilith fell in love with a human, she was severely punished for trying to cure his illness, which sparked a war with all the brothers fighting against their father. During what became known as the Great Celestial War, he and Lilith were nearly killed before Beelzebub made the choice to save him, knowing he couldn't save both Belphegor and the mortally wounded Lilith.

Many years after settling in at the Devildom, Diavolo proposed an exchange program with the other worlds. While the other student council members were for it, Belphegor was strongly against it. After the meeting, he pleaded with Lucifer to make Diavolo change his mind, but Lucifer refused.

When Belphegor reminded him about Lilith, Lucifer questioned what she had to do with Lord Diavolo's goal. Lucifer's dismissal of their sister sent Belphegor into a rage and he threatened to go to the human world and destroy everyone in it, only to be subdued and imprisoned in the attic until he changed his mind.

In Obey Me! Till Death Do Us Part (which takes place half a year later), Belphegor has graduated from RAD and is working as a fortune teller.

Always napping and constantly sleepy, Belphegor is the second youngest of the demon brothers but ranked as seventh due to his powers.

Belphegor sometimes has a brisk temper, but he's also proactive, efficient, sensible, and mellow. He isn't particularly sociable, but makes an exception for MC, who he likes to cuddle and take naps with. He also lies about the fact that he doesn't like to be pet. He isn't the type to say sorry or accept apologies from others, for he sees an action or gesture as an act of forgiveness far stronger than words.

Belphegor is rebellious and he does not care for any higher authorities, especially Diavolo and his whims. He is naturally manipulative and a great actor, posing to MC as a human prisoner of Lucifer's when they first met. It wasn't until MC identified him as Belphegor by recognizing his portrait that he admitted his identity. Additionally, it's mentioned by several of his brothers that he has the ability to manipulate them as well, using this ability to get out of things he finds tedious. He is supposedly a yandere character. This is based on the title of his Japanese card "The Yandere Seventh-Born" ("The Catnapping Seventh-Born" in English).

As seen in both the Devilgram Searching for Jack and in the chat Belphie's Artistic Skills, Belphegor has no artistic skill.

Belphegor has dark indigo-grey, white-tipped hair with long bangs that cover his right eye, and violet eyes with a pink gradient like his twin Beelzebub. Like all of the demon brothers, Belphegor paints his nails and specifically wears cerulean blue nail polish. Asmodeus claims that Belphegor has the nicest smile. Belphegor wears a hooded shawl jacket with one blue and white striped pocket on the left side of the chest. The inside of the hood is in the color of bright blue. The jacket is buttoned in the middle; the third button is the one enclosed. The jacket's cuffs are white and it also has two white stripes on the right sleeve. He wears yellowish-brown pants and brown laced leather boots that reach his knees.

When in his casual attire, Belphegor carries a cow-patterned pillow with a cow tail strapped to it at all times.

Name: Belphegor. Title: Avatar of Sloth. Nickname: Belphie. Gender/Sex: Male. Species: Demon, Angel (Former). Status: Alive. Birthday: March 11. Zodiac Sign: Pisces. Likes: Naps. Dislikes: Diavolo. Symbolic animal: Cow(banner), Bear(battle).