『Diavolo』

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.

As he tells MC in Lesson 56, Diavolo grew up very sheltered and isolated. His mother died after giving birth to him, and his father was always very strict with him. He never had the chance to speak to anyone outside the castle until he met Barbatos. After meeting him, Barbatos began to tell Diavolo stories about the outside world, which he liked so much that he asked Barbatos to stay with him. Although this was always refused by Barbatos, Diavolo never gave up. Eventually, he convinced Barbatos to stay by telling him that he would not become the Future King of the Devildom otherwise.

Little is known about Diavolo's past, but his goal has always been to build a better relationship between the three realms. He had met Lucifer when he was an angel in the past and was quite courteous towards him, despite the high ranking angel's contempt for him.

After the Great Celestial War, when the brothers fell from grace, he and Barbatos appeared before Lucifer and a dying Lilith in an area which would later be RAD's colosseum. He offered to help Lucifer's sister if he would pledge his loyalty to him. Then Diavolo had Lilith's soul reincarnated as a human.

Although his father, The Demon King, is still alive, he has no interest in the affairs of the three worlds. He allows Diavolo full reign over the Devildom, choosing instead to sleep at the bottom of the Devildom.

As a result, it is taken as truth that Diavolo will be crowned as the Future King of the Devildom. As such, Diavolo has begun strengthening the Devildom's relationship with both the Human World and the Celestial Realm through the exchange program, as he believes that the three worlds should live harmoniously with each other.

Despite being one of the most powerful demons in the Devildom as well as the Future King, Diavolo takes on a surprisingly fair and compassionate, if not joyous, attitude at almost all times. However, that is not to say he is a soft or lenient ruler, as even without the threat of retribution from Lucifer, all demons appear respectfully intimidated by him.

Diavolo proves to have much more wisdom than his cheerful demeanor suggests. He shows moments of solemn clarity in which he correctly predicts events that will occur in the future either due to his subtle encouragement or his intentional lack of intervention. He has the ability to tell if someone is telling the truth and has made a rule for himself to never tell a lie.

The goals that Diavolo sets for himself, his fellow demons, and the three worlds at large, appear to be pursued with the utmost best intentions. This is evidenced by the fact that so far he has only ever done what he believes is best, with the desire to improve the lives of those he rules over, even if the process is painful.

Sometimes Diavolo may take statements literally. An example of this occurs in the chat A Task Meant for Levi when Leviathan says that he would "kill" for a new piece of technology to mess with. Diavolo shows great concern for Leviathan's mental state and Leviathan has to clarify that he is not actually having violent urges.

Diavolo has layered, red hair with his bangs parted to the left side, tan/dark skin (depending on his form), and pale golden eyes. Like the brothers, he too has painted nails - black, in his case. Unlike the other Devildom students, Diavolo wears a special red RAD Uniform with a blue ribbon accent. He pairs it with a formal black shirt with gold button-down collars as well as a neat white tie with a tiepin underneath.

Name: Diavolo. Titles: Lord Diavolo, Future King of the Devildom, Student Council President. Nicknames: Lordy McLordface,The Young Lord (by Barbatos), Young Master (by Barbatos). Gender/Sex: Male. Status: Alive. Species: Demon. Birthday: October 31. Zodiac Sign: Scorpio. Likes: Tea made by Barbatos. Dislikes: Pickles.

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.