Lesson Overviews

Lesson 1
MC awakens inside the assembly hall where the officers of the student council hold official meetings, first greeted by Diavolo, the ruler of Devildom. Diavolo welcomes MC to the Royal Academy of Diavolo a.k.a. RAD. MC is interrupted and introduced to Lucifer who is the Avatar of Pride, the vice president of the student council and Diavolo’s right-hand man. Lucifer welcomes and explain to MC that Diavolo believes that demons should start strengthening their kind’s relationship with both the human world and the Celestial Realm. Lucifer states that they have sent two of their students into the human world and two on the Celestial Realm. MC is one of the four students welcomed to RAD, two which came from the human world and another two from the Celestial Realm. MC’s period of stay is one year, where they would have to work on the tasks received from RAD; after that they would have to write a paper about the their exchange program in Devildom.

Lucifer introduces MC to his brother Mammon who is the Avatar of Greed. MC is also given a D.D.D a lot like a cellphone in the human world. MC calls Mammon through an outgoing call, repulsive of the idea being in charge of the human and does not believe MC; Lucifer snatches the call and threatens Mammon to come. MC is then introduced to the other brothers of Lucifer; he first introduces Asmodeus, the fifth eldest and is the Avatar of Lust. Second, he introduces Satan, the fourth eldest and the Avatar of Wrath. Lastly he introduces Beelzebub, the sixth oldest and the Avatar of Gluttony. Lucifer states that there are seven brothers and he is the eldest, he also explain that Mammon is the second oldest brother and will be joining them soon. Diavolo states that the brothers will keep MC safe and would also be staying with them in the House of Lamentation. Lucifer gives MC a way to communicate with the others by handing out their phone numbers in your D.D.D

Mammon arrives at the assembly hall and Satan introduces him as the Avatar of Greed, Lucifer punches Mammon for threatening MC. He is ordered by Lucifer to be in charge of MC during the whole exchange program. Lucifer then explains MC’s tasks which is to polish your soul nicely for demons likes humans with nice souls and said that other demons at RAD also have tasks assigned to them. Lucifer also states that MC would not be doing the tasks alone for the human does not posses any magic like the other exchange students in the human world, so MC is lent with powers possessed by the brothers. The tasks consists mainly of dance battles, and to use the powers lent by the brothers you must use special cards, these cards could be summoned through the app in the D.D.D called Nightmare. Diavolo states his dream where Humans, angels, demons in a universe accepts the other and brought together as friends.

MC arrives at the House of Lamentation with Mammon; he states that it is also the only dorm that is reserved for the student council members. Diavolo has his own castle so he does not live among the brothers. MC meets Leviathan, who's the Avatar of Envy and the third oldest brother. The two get into an argument where Levi states that Mammon owns him money to buy a Blu-ray box set. Mammon uses MC as a distraction to get away from Levi, he later send MC a text that he had some business to take care of.

Leviathan drags MC into his room, he is revealed to be a huge otaku and calls other people normies; he is also a huge fan of the series the Tale of the Seven Lords (TSL). He then explains MC about TSL written by Christopher Peugeot. He later explains to MC that he lent Mammon money and wants him to pay it back. Levi tells the story why he hates Mammon; it is revealed that Mammon won a prize in a convenience store promotional campaign, if they bought something they could reach into a box and pull out the grand prize to be Seraphina figurine. Mammon refuses to give the figurine to Leviathan so he snuck into Mammon’s bedroom only to find the figurine just lying on the floor gave Leviathan threw into a fit and attacked Mammon. Leviathan advises MC that a human can make a pact with a demon and bound him to service, and making a pact with Mammon ordering him to give his money back. Leviathan then explains to MC his plan on how to make a pact with Mammon by having some leverage.

Lesson 2
The lesson starts with 2 passerby demons gossiping about MC. MC meets Solomon for the first time, an exchange student from the human world. He hands MC their dropped D.D.D. and leaves. MC then runs into Lucifer, and remembering Leviathan's advice, discreetly asks him about the whereabouts of Mammon's precious credit card, Goldie. Lucifer gives MC a hint as to where Goldie might be, which (in the hard lessons) causes quite a bit of discussion between Solomon, Asmodeus and Satan. Asmodeus says that Lucifer have taken a liking to the MC. It's mentioned in the story that Solomon was already in a pact with both Asmodeus and Barbatos.

Later on, Leviathan messages MC to go to the kitchen, having a hunch about where Goldie's hidden. Beelzebub is eating in the kitchen as usual, and MC asks him who's the seventh brother. Beelzebub warns MC to never mention him in front of Lucifer. Leviathan finds Mammon's credit card in the freezer after Beelzebub leaves. But Mammon shows up then, and after he sees Golide, he even goes down on his knees to get Goldie back. He also agrees to make a pact with MC when Leviathan threatens to tell on Lucifer. The next day, the brothers laugh at Mammon and tease Leviathan that he was won over by the MC. Unfortunately, Lucifer walks into the dinning room while Mammon is criticizing him. The brothers continue to tease Mammon even after he's hit by Lucifer. Mammon stomps off with MC and claims that he would not care if MC got eaten by some demon in Royal Academy of [[Diavolo|RAD]]. MC commands Mammon to 'stay!' and true enough, he could not leave.

At RAD, MC meets and chats with Diavolo and Barbatos, Diavolo's steward. Simeon and Luke (the two angel exchange students from the Celestial Realm) also join the conversation. Both Diavolo and Lucifer makes fun of Luke, calling him a 'chihuahua'. Luke retaliates by saying that he reports directly to Michael the Archangel, implying that he is a high-ranked angel. When MC is left alone with Luke, he warns them to never trust a demon, especially when that demon is Lucifer. The first bell rings and they part ways.

Later that night, MC hears someone calling for help. When they followed the calls, MC reaches a staircase. Before they could climb the stairs, Lucifer appears and tells them to go back to their room. The lesson ends with MC's flashback on Luke's words to never trust a demon.

Lesson 3
The following night, MC tries to visit the staircase, only to be blocked by Lucifer again. Lucifer emphasises that MC should not try to go up again. MC comes to the conclusion that they would not be able to reach the top of the staircase unless something is done to Lucifer.

The following morning, Mammon eats breakfast with MC and says how much he would like to eat MC. He then goes on to critize his demon brothers, like how Leviathan's haircut is so lame and Satan's horns look stupid. Mammon refuses to leak any information when MC asks him what was at the top of those stairs. MC then taunts and makes fun of Mammon, and in his rage, he says that Lucifer can be distracted with a vinyl edition copy of the TSL soundtrack. MC uses the power of their pact to drag Mammon to Leviathan's room to get the soundtrack.

As MC and Mammon discuss how to get into Leviathan's room, Solomon appears, invited by Leviathan to his room. Solomon manages to enter Leviathan's room using a secret phrase as proof that he's a TSL nerd, leaving MC and Mammon outside. Later that night, MC, Mammon and Beelzebub (who's only there for the popcorn) keep a 'TSL Full Series DVD Marathon Night' that lasts for 12 hours. The next day, MC competes with Leviathan to see who is the biggest TSL fan. Before that, MC meets Beelzebub and Satan, who both give them tips to win. Beelzebub suggests to work Leviathan into a jealour frenzy, and Satan tells MC to ask Simeon on the unreleased contents of TSL. On the day of the competition, Diavolo acts as the judge, Satan as commentary, Beelzebub as guest demon and Asmodeus as the host. Asmodeus asks easy questions from MC, and hard ones from Leviathan. MC proceeds to pull out their trump card, ending the lesson on a cliffhanger to be continued in lesson 4.

Lesson 4
Turns out, MC 's trump card is the knowledge of the summarization of the major plot developments in the as-of-yet unreleased TSL Volume 9. Leviathan though that MC was lying until Diavolo, who has the ability to discern whether someone is telling the truth, confirmed that MC was telling the truth. The idea of MC being a bigger TSL fan than him successfully sent Leviathan into a jealous frenzy, revealing his demon form. Just as he was about to attack MC, Lucifer revealed his demon form and stopped Leviathan. The TSL quiz ended on a draw. After the TSL marathon night, it seems that Mammon and Beelzebub constantly hung around in MC's room. Mammon says something to MC after Beelzebub left the room. Later, Beelzebub catches Mammon searching MC's room for things with monetary value, wanting to sell MC's uniform and claiming that he would even sell MC if there was any profit in it. Beelzebub came to the conclusion that Mammon likes MC so much, he can't help but dig through their things. Mammon becomes desperate to deny it. Beelzebub takes a picture of Mammon smiling at the thought that MC likes him and sends it to the demon brothers.

Later, MC meets with Leviathan in the Planetarium. Since Leviathan now views MC as the bigger TSL fan, he keeps his promise to enter a pact. MC borrowed Leviathan's TSL soundtrack successfully, and lends it to Lucifer. He told MC that he would not leave his room that night, but warns MC not to climb the stairs to the attic. However, MC climbs the stairs and finds someone trapped in the attic, saying that he was a human just like MC. He says that Lucifer imprisioned him in the attic long ago, and he's been stuck there ever since. He asks for MC's help to free him, and in order to do so, MC needs to form a pact with Lucifer and his six brothers to obtain their consent. He tells MC to go for Beelzebub next. The next morning, Lucifer asks MC what they had done last night, and told them to just focus on surviving in Devildom and return to the human world at the end of the exchange program. Later, MC, Mammon and Beelzebub meets Simeon and Luke, and the angels invites them to a camping trip. Later that night, MC lies in bed thinking about what the stranger in the attic had said, when they received a message from Mammon telling them to meet him in the kitchen. Mammon finds Beelzebub's custard in the fridge and urges MC to eat it. MC eat Beelzebub's custard, and Beelzebub appeared in the kitchen, asking angrily if Mammon ate his custard. Lesson 4 ends with Beelzebub revealing his demon form, not believing that his custard was eaten.

Lesson 5
MC, Mammon and Beelzebub stood in Lucifer's room as Lucifer lectures them on what they had done wrong. The kitchen was destroyed when Beelzebub went on a rampage, and since MC's room was on the opposite side of the wall, MC's room now lacks a wall. Lucifer told them that MC would be staying in Beelzebub's room for the time being. There were two beds in Beelzebub's room. The bed on the left belongs to Beelzebub, and the bed on the right belongs to Belphegor, Beelzebub's twin brother. Belphegor was said to be in the human world as an exchange student along with another demon, Diaval. The brothers used to have a sister, Lilith, who was especially close to Beelzebub and Belphegor. MC later realized that the occupant of the attic room is actually Belphegor through a portrait of Belphegor in the portrait room. MC went back to the attic and true and he indeed is Belphegor, the avatar of sloth.

The next morning, MC eavesdropped on a conversation between Lucifer and Beelzebub on how Belphegor has been and that Belphegor had tried to stand in the way of Diavolo's dream. It seems that the demon brothers were originally angels up in the Celestial Realm and Lucifer had pleged loyalty to Diavolo when they ended up in the Devildom. MC decided to help Belphegor in order to resolve the conflict between the twins and Lucifer. Later on, Luke messaged MC that he was outside the House of Lamentation and he needed to spend the night in MC's room. Since MC's room was destroyed by Beelzebub, Luke had to stay with MC in Beelzebub's room. During breakfast time, both MC and Beelzebub ate less than usual, wanting to bring the food back for Luke. Beelzebub having uneaten food left on his plate caused a commotion between Mammon, Satan and Asmodeus. On the way back to Beelzebub's room, Luke was spotted roaming the hallway and looking inside rooms like Satan's. He managed to see his room as well as Purgatory Hall from the House of Lamentation. Back in Beelzebub's room, Beelzebub announced that Lucifer is having a surprise inspection to check if anyone is out past curfew. Lucifer also checks inside the room itself, and found a witch that had transformed into a spider in Asmodeus' room. Beelzebub shoves Luke into a closet, where Luke had disappeared when Lucifer ordered for it to be opened. Luke did not come back that night. The next day, Simeon asks MC and Beelzebub to take care of Luke until he is ready to go back, but both MC and Beelzebub could not tell Simeon that Luke had disappeared. Later, Beelzebub and MC searches around the house but still could not find him. They met Satan on the way. When they reached the entrance hall, they saw that the decorative dollhouse of the House of Lamentation had an extra room in it, a room that does not exist.

Lesson 10
Lucifer, Mammon, Leviathan, Satan, and MC entered the game Doji⭐️Maji⭐️Memorium.

Lesson 11
Lucifer (in Satan's body) buys Mammon and MC food at a restaurant. After eating, it's revealed he did it so that Mammon and MC would go to the human world with him. There he plans to find the witch that created the curse so that it can be lifted. However, only certain demons can travel to the human world directly and since Lucifer is in Satan's body he can't. Satan (In Lucifer's) arrives and they go to the human world.

Lucifer buy four matching keychains for them at the train station. They are in a private cabin on the train. Mammon goes to find the dining car so he can take a picture and brag to Beel. Mammon gets accused of murder after entering a private car. Lucifer, Satan and MC arrive at the scene after hearing screaming and a description of a person that fits Mammon.

In the car they encounter Lucas, Noah, Sophia and a dead Grisella, the witch they were looking for. Lucifer uses his powers to hypnotize the three humans to go away. Back in their own car they encounter the ghost of Grisella who wants them to solve the murder in exchange for lifting their curse.