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 the 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 the 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 Leviathan states that Mammon owns him money to buy a Blu-ray box set. Mammon uses MC as a distraction to get away from Leviathan, 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 fan of the series the Tale of the Seven Lords (aka TSL) as he goes on a rant about the series. Later he explains to MC that he lent Mammon money and wants him to pay it back. Leviathan 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 refused 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 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 next 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 jealous 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 the 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 eats Beelzebub's custard, and Beelzebub appears 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 6
MC and Beelzebub finds a secret room, a copy of Lilith's room back up in the Celestial Realm. MC asks Beelzebub to know more about Lilith, and he described what happened during the Celestial War. Mammon suddenly calls MC and tells them to hurry to the underground tomb. A series of events occurs, involving Lucifer, Beelzebub, Luke, MC and the grimoire. MC passed out and when they wakes up, they make a pact with Beelzebub as his way of saying thank you. Beelzebub also takes MC to Hell's Kitchen to eat, but Mammon and Leviathan tagged along. The four eventually talked about why MC wanted to make a pact with the brothers, which is to impress Lucifer and help him make up with Belphegor. Mammon and Leviathan joined in on the operation. When they got back to the House of Lamentation, Lucifer appeared and told MC that their room has been fixed. On the last night staying in Beelzebub's room, he held MC's hands as he tries to fall asleep. That night, he had a different dream from what he usually has.

The next morning, breakfast with the brothers was awkward and uncomfortable. Just as MC was about to head off to class early, Lucifer told them to meet him in the music room. A conversation occurs and Lucifer wants to treat MC to a meal to make it up to them. Later in the student council room, Diavolo announces an exchange party between demons, angels and humans to be held at the Demon Lord’s Castle. They will spend several nights there and attend several events such as a dinner party and a formal dance. MC goes to the attic and Belphegor tells MC to search for clues why they were chosen for the exchange trip at the retreat.

Lesson 7
MC and the demon brothers arrives at the Demon Lord’s Castle, followed by Solomon, Simeon and Luke. Barbatos explained that there would be a tour around the castle and different cusines would be served on the three different days: Devildom cusine by Barbatos, Celestial Realm food by Luke and the Human World food by MC (for lunch on the last day). There would be a scavenger hunt on the second day along with a dance after that. Barbatos proceeds to assign rooms. MC shares a room with Simeon and Asmodeus. Mammon demands to switch rooms with Asmodeus, and Asmodeus refuses to see Mammon's reactions.

On the first day, everyone goes on the tour of the Demon Lord's Castle conducted by Little D. No. 2. The tour starts with the portrait of the current Demon King, Diavolo's father. Diavolo mentioned that he hadn't seen him in several hundred years as he is slumbering at the bottom of the Devildom. While they were passing through the stairways, Helene recognized Asmodeus and as a result of her leftover powers, Mammon, Leviathan, Beelzebub, Solomon, Asmodeus and MC was pulled into the painting, ending up in the underground labyrinth. Lucifer cotinued the tour regardless. A snake, Leviathan's Henry 1.0, rests in the labyrinth and chased after the group who fell in. Asmodues, who's power was amplified by Solomon's magic, was able charm the snake and let it show the way out. Later that night, Mammon showed up in MC's room, wanting a pillow fight. However, Lucifer overheard Mammon badmouthing him and pulled him to the room Diavolo and Lucifer shares. Simeon comments that they could sleep peacefully that night.

Lesson 8
The second day of the retreat arrives. Mammon didn't seem to get any sleep last night due to Lucifer, and the rest of the brothers had fun interpreting what Diavolo had said. Since the iternary for the day was scavenger hunt, each group will be given riddles to solve for a historical item in the castle and take a picture of it. However, with Asmodeus disrupting things, such as charming a goddess statue so that she wouldn't go back to her original pose, Luke's group is not able to complete their riddle solving. Asmodeus leaves so that he wouldn't have to heard Satan's lecturing. MC follows Asmodues. MC tries to make a pact with Asmodeus, but he said that only on the condition that they manage to outsmary Lucifer, such as getting a picture of Lucifer's sleeping face. Later, Luke serves dishes from the Celestial Realm that he made for dinner on the second day, and MC tries to get a hint of where Lucifer's room is.

In lesson 8-8, Diavolo transforms the Hall and fills it with guests from across the Devildom for the formal dance. The demons and even Diavolo transforms into their demon forms for the dance. Mammon nervously asks MC for a dance, claiming that as long as MC doesn't have a partner, he would pair with them for the dance. Satan and Leviathan teases Mammon and Lucifer appears, telling MC to dance with him immediately, shocking Mammon. As Lucifer and MC dances, he lists the reason why one might ask someone else to dance, including the reson that they want to have a private conversation. Words were exchanged before Solomon appears and invites MC to dance. Lucifer leaves, not befoe giving a final warning to MC. Solomon talks with MC and lends them some of his powers for six hours.

Later that night, MC, Mammon, Leviathan and Beelzebub commences 'Operation Photograph Lucifer Sleeping'. When they entered what is supposed to be Lucifer's room, Cerberus appeared. When the four found a door to escape from, they rushed through it only to fall back into the underground labyrinth with Henry 1.0 chasing them. Using Solomon's borrowed powers, MC summons Asmodeus to tame Henry 1.0. They discover that amount of MC's magical powers was much more as compared to Solomon's. When the four returns to the castle, Lucifer explains that if someone opens his room door without knocking, it transports them straight to Cerberus's room to prevent thief of the castle's valuables. Having seen the amount of MC's magical powers, Asmodeus was impressed and decided to make a pact with MC. MC now has a pact with four demons.

Later that night, Asmodeus fusses over MC, even asking to sleep in the same bed as them. Mammon suddenly appears, kicking the door open and trying to stop Asmodeus. Satan and Leviathan appears, surprised at the sight before them. Being annoyed at Asmodeus's proximity to MC, Mammon threw a pillow in Asmodeus's face, causing a pillow fight to escalate between Mammon, Asmodues, Satan, Simeon, Luke, Solomon, Lucifer and Diavolo. After the pillow fight ended and everyone went to bed, Diavolo and Lucifer discusses MC's pact making in the garden. Lucifer sighs and asked Diavolo why he had to pick MC as the exchange student. Turns out, Satan and Barbatos have been eavesdropping on the conversation.

Lesson 9
Returning home to the House of Lamentation after three days away on a retreat, Asmodeus questions MC why they want to make a pact with all the demon brothers; MC responds with wanting to get Lucifer’s respect. Satan along with Lucifer asks what is the point of getting Lucifer’s respect and what MC is trying to accomplish. Satan states that he would also be making a pact with the purpose of making it hard on Lucifer. Satan & Lucifer get into an argument which ends with Lucifer wanting to kick Satan out of the house and MC tries to calm them down which angers Satan more and he ends up leaving.

The scene moves to MC’s bedroom along with the other brothers except Satan and Lucifer, where MC tells that the plan is to get Lucifer make up with Belphegor and why MC wants to make pacts with all of the brothers. Asmodeus states that Satan will do anything to make Lucifer upset - even making a pact with MC. But Beelzebub contradicts the idea of earning Lucifer’s respect in that way not if Satan makes a pact with a reason like that. MC asks why Satan hates Lucifer; Asmodeus answers MC by stating that the more people are alike the more they hate each other, Leviathan states it’s more of an Oedipus complex thing. Mammon explains that during that time Lucifer was really mad at their father and Satan was born from that Wrath. Beelzebub supports Mammon’s statement saying that Satan was nothing more than emotion itself, Satan was wrath. Asmodeus & Leviathan agrees saying they basically raised Satan during that time, but Satan was especially influenced by Lucifer.

MC goes to Satan’s bedroom, where Satan is trying to gather which books to take with him since he can’t take them all. Satan warns MC of one book in particular as it's a forbidden book where if two people touch it, they’ll switch bodies. Satan shares with MC that their father was the one who bestowed upon their names based on their power as demons, from most to least powerful. Therefore Satan was the last to be born into the world and the fourth most powerful, he was born from Lucifer himself which irritates him very much. MC disagrees with Satan for making a pact for the sole reason to irritate Lucifer, this angers Satan but he's abruptly stopped by Lucifer. The two begin a heated argument and MC tries to calm them down, as Satan’s wrath grows stronger the books all around the room starts to fly off the shelves and shooting towards Lucifer. Lucifer grabs one of the books and recognizes it's the forbidden book Satan has warned MC about before. A flash of white appears and the two brothers Satan and Lucifer has switched bodies. Satan (now in Lucifer's body) imitates Lucifer jokingly and states that the effect of the body switch lasts for several days. Lucifer (now in Satan's body) still suggests they go to school even if they have switched bodies for he does not want Diavolo asking questions. Lucifer insists to keep an eye on Satan so he doesn’t get into any trouble while he is in his body. Lucifer implies that they must stay in one’s particular room Satan is appalled by the idea. The other four offers and suggests their rooms but in the Lucifer decides it’s best if they both stay in MC’s room.

In MC’s room, Lucifer discusses on how things would work now that they have switched bodies. He declares two fundamental rules they must abide to: First, neither him or Satan is allowed to go into each other’s rooms unless the other is present as well. Second, they would be avoid doing anything that might attract attention while at school. Mammon feels relieved that even though Lucifer is scolding him he doesn’t feel inferior nor scared of his nagging. The next day at school, Lucifer opens up to MC saying he doesn’t trust the two knowing Satan and Mammon will try to make the whole situation funny, he then wants MC to keep an eye on the two. Diavolo appears and greets Satan, he asks what has happened to him today for he was always at the assembly hall first thing in the morning. Satan mocks the impression of Lucifer in front of Diavolo which made him realize that him and Lucifer had their bodies switched. Diavolo reminds Lucifer that he has been scheduled to give a speech to the entire student body the day after tomorrow, the speech is a report to the full student body on the current state of the exchange program and how all of their exchange students are doing. Lucifer concludes that if they haven’t switched back to normal then Satan would have to deliver the speech as himself. MC suggests to talk things out with Satan they later find Satan in MC’s room.

Satan continues to mock Lucifer by making impressions and saying things Lucifer normally wouldn’t say even inviting Leviathan and Beelzebub to harass Lucifer. Mammon plans to take advantage of the fact that with their bodies switched they could infiltrate partying with the other demons & accepting bribe from the RAD newspaper club. The fight between Satan and Lucifer gets worse in MC’s room. MC can’t fall asleep so they go out the hall where they hear a voice. MC finds Mammon hanged right-side up by Beelzebub ordered by Lucifer. MC helps Mammon break free but on one condition if he agrees to convince Satan and Lucifer to make up the they’ll let him down. Mammon agrees with MC’s condition and has had an amazing idea on how the two would make-up.

Lesson 10
In Leviathan’s room, Mammon presents to MC a game named Doji⭐️Maji⭐️Memorium (Dogi Maji for short). Anyone who registers to play is actually pulled into the game world for real. Mammon plans to have Satan and Lucifer work together toward a common goal while playing the game. Lucifer, Mammon, Leviathan, Satan, and MC enters the game.

Inside the game, MC and the others are transferred in school Leviathan explains that Dogi Maji is a school dating sim; one character is designated as the heroine and the others have to work hard to increase your favorability score with her higher and higher, in the end the player must go up the Roof of Legend and profess their love for the heroine, and if she accepts them, they win. MC is the designated heroine, Lucifer is no longer in Satan’s body in the game as well as Satan in Lucifer’s body. Satan challenges Lucifer on who would get to raise intimacy with MC first but the other two refuses to be beaten.

In the classroom, MC interacts with Mammon, which affects his intimacy level. On the hallway, MC bumps into Satan and helps with the stuff they are carrying to the classroom also affecting his intimacy level. On the school grounds, Leviathan makes MC a homemade Ruri-chan themed three-layered bento box lunch which affects the intimacy level. MC heads up to the roof to find Lucifer, where he's laying on a bench taking a nap. Lucifer skips class because there is no Diavolo in this world so he could do whatever he wants without worrying about being a disgrace to him in any way. MC's reply also affects his intimacy here.

(Lesson 10-A) Back in the House of Lamentation, Asmodeus is looking for MC along with Beelzebub. They head towards Satan’s room but only find it in a chaotic state. As the two are cleaning up Satan’s room of books they happen to touch the forbidden book that made Satan and Lucifer switch bodies. Beelzebub and Asmodeus has also switched bodies. (Lesson 10-C) The two brothers become curios about each others bodies, Asmodeus (in Beelzebub's body) persists taking Beelzebub’s clothes off wondering how he has pecs even though he eats a lot; Beelzebub (in Asmodeus's body) on the other hand is wondering why is Asmodeus’s body very soft. Suddenly the two feel hungry and they come to understand what it means to be in each other’s shoes. In a flash, both return to their respective bodies. The forbidden book looks more worn out than usual, Asmodeus states that the more they use it to switch bodies the more worn out it becomes until it eventually can’t be used anymore.

Back in Dogi Maji, it is the final day where the players must profess their love to the MC. Lucifer begins to be nice to MC for the sole purpose of ending the game immediately. Satan confronts MC in the school hallway and apologizes about Lucifer and for getting MC caught up in a weird business. MC tells him to wait and that he doesn’t have to force himself to like someone he doesn’t. MC also tells him that Lucifer doesn’t see Satan as a child as much as he thinks and he only wants to look good in front of Diavolo as his right hand man. Satan is convinced and thanks MC for the refreshing point of view of the situation is and was the first person to tell him this.

On the rooftop, monsters start popping out of nowhere over the school and has changed the game into a ultra-hard survival fight. The monsters start to devour computer-controlled classmates and the five are barely able to survive. Leviathan seems to be excited of the crazy plot twist in a simple dating sim, not to mention how bloody the game was. Satan gives an idea to the group that they are likely meant to have survived and seems to have hit the final battle. The last boss appears to be Cerberus, but Satan suggests that it is not the same Cerberus as the one they have in the Devildom. Lucifer commands Cerberus to sit which angers the demon dog more. Cerberus charges toward Satan and is about to strike, Lucifer halts and commands Cerberus to sit once more and threatens the dog if he does anything to harm his brother. Cerberus whimpers and is calmed down. The screen is filled with confetti stating that the Mission is Complete. Back in Leviathan’s room, Satan and Lucifer remains to have their bodies switched in the real world. Leviathan suggests that the two might be better off inside the game for the time being, Mammon warns them about Cerberus but Satan disagrees for he has Lucifer beside him. The two brothers seems to have an agreement with each other and gradually accepts one another. Leviathan later reviews Doji Maji online in Akuzon.

Lesson 11
Somewhere in the Devildom, Lucifer, who’s still in Satan’s body, MC, and Mammon walk together and speak about Satan. Then, Lucifer takes them to a restaurant. After eating, it’s revealed he did it so that the two others will compensate him and go to the human world to help him find the witch who created the curse of the body switch in order to lift it; Mammon is pretty reluctant about going there because he’s afraid of witches. However, only certain demons can travel to the human world directly and since Lucifer is in Satan’s body, the magic doesn’t recognize him and they can’t travel. Satan suddenly arrives and decides to help them since he's in Lucifer's body, which means the eternal magic seal will let him pass. Thus, they travel together.

Once in the human world, Mammon’s attitude changes completely and he enjoys himself. At Victoria Station, Lucifer buys four matching keychains for the entire group, which is pretty surprising that he spends money for them, especially when it was Mammon’s wish. Next, they’re in a private cabin inside a train. Mammon leaves them to find the dining car so he can take a picture of the food and brag to Beelzebub. However, he stumbles in to the wrong room and gets accused of a woman's murder. Lucifer, Satan, and MC arrive at the scene after hearing her last scream and a description of a person that fits Mammon.

They meet Lucas, Sophia, Noah, and the dead woman, who appears to be Grisella, the witch the group was especially searching for. Lucifer uses his powers to hypnotize the three humans so that they go away. Back in their own car, they hear the ghost of Grisella, who wants them to solve her murder in exchange for lifting the curse of the body switch. All the demons decide to torture the three suspects, but MC wants to find another way less violent; “the human way”. They question Grisella and Mammon, and with the information the demon brother had said, they guess who’s the killer. As the three humans gather, the witch warns MC about Lucifer, saying he’ll soon lose the trust he puts in them.

Once in front of the suspects, Satan decides to explain MC’s thoughts and claims the killer is Noah. It turns out to be right, as he says he truly wanted to become Grisella’s apprentice but the witch didn’t want to take one because she predicted she’d die in the train, which broke the man’s heart; ironically, it’s exactly why she was killed. Back in their car, Grisella lifts the curse of the body switch. Surprisingly, Lucifer asks Satan to do the speech about the report he’s supposed to do tomorrow, and his brother agrees with confidence.

Lesson 12
Lucifer proposes a toast with everyone (Leviathan is absent) along with Diavolo for lifting the curse that had Lucifer and Satan in each other’s bodies, Lucifer then congratulates Satan on delivering the speech to the entire student body. Lucifer and Satan both jokingly impersonates each other confusing the others and everyone seems to be in a good mood tonight, and they’re all enjoying themselves. Diavolo thanks the MC for among other things seeing how happy Lucifer seems to be. MC asks Diavolo on how they were chosen to be an exchange student in the first place, he later explains that it wasn’t him that chose them but Lucifer.

(Lesson 12-A) A conversation between Diavolo, Barbatos, and Lucifer are taking place. Lucifer denies he had an exciting adventure by switching bodies with Satan, surviving a video game, and even visiting the human world. Diavolo and Barbatos point out they are jealous of how Lucifer enjoyed himself in the human world and he clearly doesn't deny that it was fun. Diavolo also asks if Lucifer bought any souvenirs with him since he has a decorative strap attached to his D.D.D. Barbatos recognizes it as Harrison Porter chocolate lizard keychain which can only be bought in a shop in London Victoria Station. He also mentions that Mammon, Satan, and MC has the same keychain as well.

(Lesson 12-C) Diavolo suggests they come to the human world as well along with Lucifer, he mentions a witch named Artemesia and how they should perhaps give her a visit. Lucifer refuses for they owe the witch a great amount for Mammon’s sake. Diavolo mentions MC and notices how well they are getting along with Lucifer and his brothers. Lucifer admits that Diavolo’s plan may be working and his brothers are starting to see humans in a new light now and it’s due to MC’s influence, he also admits he trusts MC now. Diavolo then proposes on celebrating along with the others at Ristorante Six. After Lucifer leaves, Diavolo seems worried about Lucifer and Barbatos suspects that what’s about to happen will wound him deeply.

At Ristorante Six, MC is having a conversation with Diavolo. He shares that he believes everyone has a mission in life. His is to bring progress and stability to the Devildom, the Celestial Realm, and the human world. Something happened once and that made him firmly believe in this. It’s possible that MC’s mission in life is to influence Lucifer and his brothers in some way. He hopes that whatever influence MC does end up having it turns out beneficial to them.

Outside of the Devildom, MC walks alongside Lucifer as Mammon, Asmodeus and Beelzebub went to go ahead first. Lucifer asks MC what conversation happened between Diavolo and themself. Lucifer also states that there was no particular reason why he ended up choosing MC for there was suddenly a breeze that blew through the window scattering the lists into the air and one of them happened to land at his feet with MC’s name on it. He also says there was nothing special with MC being chosen as an exchange student but MC is somewhat special to him on a personal level. Lucifer’s phone starts ringing and it turns out to be a call from Leviathan; back at Leviathan’s room, he seems to be skeptical for they aren’t picking up their D.D.D. Leviathan then screams and disappears.

At the House of Lamentation Lucifer is trying to find Leviathan in his room, only finding his D.D.D laying on the ground and Leviathan himself is nowhere to be seen. Lucifer then notices that Beelzebub is also missing. In front of the House Of Lamentation, Asmodeus complains that searching for the two at this late hour is bad for his skin. Lucifer suggests that they split up, having Satan and MC to search for the two.

Lucifer then recalls the story about the House of Lamentation; It was long ago, back before the place was even called the House of Lamentation. The house was built on the outskirts of a village in the human world, at the same time a married couple and their seven children lived there along with one servant. They appeared to be a happy, well-off family that enjoyed living out the country. However, one day the oldest son came running into the village constable’s office looking pale. He delivered a horrifying piece of news that their servant has murdered everyone in his family and then took his own life. The constable’s men went back with him and were greeted with a ghastly sight. Every person in the family had been murdered, each in a different way and in a different location. The servant was found in his room hanging a rope around his neck. The constable concluded the servant must have reasons that plotted to kill his masters and take his own life, and since the perpetrator was dead they decided that the case was closed. However, sometime later several facts came to light that gave rise to new doubts. The only person who wasn’t killed was the oldest son who had been on extremely bad terms with his siblings. He had also purchased a gun just like the one used in the murders shortly before they occurred. A postman was also a witness seeing the servant argue with the oldest son prior to the killings which led people to think that maybe the oldest son was the true killer. In the end, the truth never came to light. The oldest son lived in the house by himself and eventually died of old age. At some point, the house was given a name “The House of Lamentation”.

Later, Satan asks MC to make a pact with him. MC is surprised and asks the reason why he suddenly wants to make a pact with them. Satan clears it up by stating that he is not doing this to make Lucifer angry. Satan decides that he won’t let what Lucifer does bother him anymore and is reminded by what Grisella said that you have to accept the hand fate deals you no matter what. What matters is how you handle it. Satan was able to face his issues because of MC, as they were the one who helped him be honest with Lucifer along with himself. Now MC has successfully made the 5th pact with Satan. Later on, the three hear screams that sound like Mammon and Asmodeus to Satan. In the portrait room Satan feels uneasy that the other brothers are disappearing. Then he suddenly disappears as well, leaving Lucifer and MC alone.

Lucifer suggests MC to go back to Leviathan’s room for he was the first to disappear. On the way back they hold hands and notice Leviathan’s PC monitor is still turned on. Lucifer recalls Levi ordering a new game from Akuzon and found the game The Demon House which sounds like a horror game that describes the situation they are in right now. Lucifer suggests MC that they complete the game and see what happens, upon searching the internet it states that in order to complete the game, you must defeat the demon that serves the final boss and the boss’s name is Lucifer as well.

In the library of the House of Lamentation, MC is with Lucifer he states that with everyone gone the MC must defeat him since he is the final boss, and to end the ridiculous game, it is either that or they fall in love with each other. Lucifer decides that he would not bother to lose face in front of Diavolo by being defeated so the only choice MC has is to fall in love with each other. Lucifer suggests if between MC and him do they really need his other brothers, so they stat by trying the fundamentals of love and go from there and it starts by getting to know each other well. Lucifer proceeds to ask MC questions; as the questions proceed MC asks Lucifer what he thinks of humans but he depicts the question as to what does he think of MC. He then explains that MC had his thoughts all he has to do was make sure they survived a year without any incidents being careful and to ensure that MC did not get into any trouble by being eaten by a random demon somewhere but in the end, MC managed to make pacts with his brothers one by one. Lucifer asks MC why’d they make pacts with them, he recognizes MC's worth but confronts them about what exactly they're trying to achieve in the long term. MC finally tells Lucifer they met with Belphegor and this enrages him.

Mammon appears along with Asmodeus, Leviathan, Beelzebub, and Satan. Beelzebub finally hears about Belphegor not being in the human world and is actually locked in the attic this enrages Beelzebub. Lucifer ends up hurting Beelzebub, and Belphegor suddenly appears along with them.

Lesson 15
Lesson 15 begins with the brothers explaining to MC why Belphegor hates humans. They talked about the time when they were still angels, when Lilith was still alive, and when Belphegor loved humans (15-2). The first four parts of the lesson revolves around the story of how the brothers got banished to the Devildom, the death of Lilith, the reason of Lucifer's loyalty to Diavolo, and Lilith's rebirth as a human.

Upon knowing the story, MC and the brothers decided to pay Diavolo a visit. They ask Diavolo to release Belphegor. Diavolo agrees but under the condition that MC completes a task — to travel back into the past and ascertain exactly who it was that released Belphegor. And so, into the past, MC goes...

MC returns to the time when the brothers are disappearing one-by-one. They learn that the brothers did not 'vanish', the act is part of their plan to get Lucifer and MC to make up. The brothers believe that they have been caught red-handed and urges MC to go back to the room and patch things up with Lucifer. So MC did, without telling the brothers about the time-traveling situation. They arrive outside the room and hears Lucifer complaining about how ridiculous the game is. Just as the pair begin to exit the room...

Lesson 16
MC hides in the secret room, a replica of Lilith's bedroom, to avoid being seen by their other-self. They're hit by Lilith's memories upon entering the room. With the memory in mind, MC heads to the attic. They touch the door to Belphegor's attic room which magically opens. They enter the room to find Belphegor sleeping.

Belphegor wakes up and realizes that he is now free and overwhelms MC with his appreciation. After all, it is finally time for him to achieve what he set out to do (16-6). He turns into his demon form and begins to ridicule humans. He laughs at MC for falling into his trap and attacks them.

Unable to withstand the pain, MC faints. They meet Lilith in a dream-like world. They learn that Lilith remembered everything after her death as a human and has been watching over her brothers ever since then. She tells MC that they are her ... which is why she will lend her power so MC can save her brothers (16-10).

MC wakes up and discovers that they are not injured despite being attacked by Belphegor. They hear arguments downstairs and heads to the source. They see an injured MC dying in Mammon's arms. MC reveals themselves to take a better look at the situation. The next second, the MC in Mammon's arm disappears. The brothers are very confused. Belphegor, determined to kill MC, begins his second attack only to be stopped by the story of Lilith (16-12).

While Lucifer is asking where MC heard the story from, Diavolo enters the scene and reveals that MC is a distant descendant of the human Lilith. He asks MC if they ever had visions of Lilith's memories. MC recalls the moment when Lucifer pledges his loyalty and allegiance to Diavolo in exchange for Lilith's life (16-15).

The brothers convince Belphegor that Lilith lived a happy life as a human and that he's supposed to be happy about it. Belphegor spills his thoughts, blaming himself for Lilith's death, and Lucifer says that he should've told them earlier. After both confessions, they host a celebration. Belphegor immediately hogs MC. When asked about the other MC's disappearance, Barbatos reveals another secret about his power — the power to select from any number of different potential realities and make any of them into the sole reality. With all questions answered, the chapter ends with the brothers fighting for MC's attention.