Suzuki Iruma is too nice and just doesn’t know how to say no. One day, he somehow gets dragged into the netherworld where the demons live. He arrives at the great demon Sullivan’s mansion where he is asked to do the unthinkable... and ends up becoming Sullivan’s grandson! He is quickly enrolled into the Demon School Babyls where Sullivan serves as chair-demon. Iruma begins his super exciting school life at demon school while trying to conceal the fact that he’s a human!

Iruma, who is going to Babirusu, wants to spend calmly so that he will not be noticed by humans. However, the entrance ceremony and a case with the entrance examination chief Asmodeus Alice have already attracted the attention of the students! First-year students Iruma and others decided to participate in the "Familiar Summoning Ceremony" event to determine the rank of the devil. The person in charge is Naverius Caluego, an extremely strict instructor in Babiru's. What kind of familiar is Iruma summoned?

Iruma, Asmodeus, and Clara end up in the Misfit Class. As the name suggests, the class is filled with a bunch of misfits and Sabnock Sabro, who wants to become the next Demon King, declares Iruma his rival. Their classes start and their first lesson is a flying race. The race was to take place in the Warbling Valley and the Cutthroat Valley. Apparently, there’s also a demon bird that lives there...

The Misfit Class is in the middle of a flying race in order to determine their ranks. Since Iruma is human, he can’t fly, so he’s riding on the back of the giant baby demon bird, but it seems to be flying off course. Meanwhile, Sabnock decides to go through the treacherous Cutthroat Valley and ends up having to battle it out with the Guardian there. Sabnock is obsessed with becoming the next Demon King, but why is he so obsessed? Are Iruma and Sabnock going to be able to make it out of Cutthroat Valley alive?

Clara isn’t amused at the fact that Ameri keeps summoning Iruma. To try to get Iruma to pay attention to her again, Clara starts to take succubus charming lessons with the succubus teacher Raim. Clara wants to get Iruma’s attention again, but apparently her sexiness is almost nonexistent. Even then, Clara sets out to charm Iruma. Will she be able to win Iruma over?

After making a promise with Ameri, Iruma sets out to try to move up a rank. Iruma finds out that there is a promotion exam in a week where they would play execution cannonball, and he also finds out it’s rather similar to a game they play in the human world. Iruma decides to train after he realizes he’s far weaker than anyone else in his class. Iruma decides that he’s not going to use magic, so he starts an intense training regimen with Opera. What does Iruma gain at the end of all this training?

The day of the rank promotion test involving execution cannonball had arrived. Iruma is ready for the match, but then ends up on different teams with Asmodeus. Despite that, the game continues with all his other classmates using their various forms of magic to play the game. Will Iruma be able to show off the results of his training?! And who will win? Iruma or Asmodeus?

Part A: A new teacher named Balse Robin, who is quite innocent and fearful of nothing, arrives! His first lesson involves interacting with familiars. Iruma turns pale at the thought of this lesson since his familiar happens to be Kalego, but... Part B: Iruma decides his next goal now that he’s moved up a rank. Apparently, there are groups at Babyls where like-minded demons gather called Battlers. Iruma shows some interest in Battlers, but then is greeted by a terrifying sound...

The Battlers’ recruiting operation, the Rookie Hunt, had begun. The seniors all come out to try to find worthy first-years to join their groups. What takes place is an immense battle! Iruma and his friends somehow make it through, but then decide to check out the various Battlers on campus. But then suddenly, Iruma’s ring goes berserk, causing him to run into a senior...

Iruma runs into his senior Amy Kiriwo in front of the Magical Apparatus Battler again. The Magical Apparatus Battler room is filled with all kinds of strange gadgets. There, Iruma hears about Kiriwo’s dreams. Babyls is about to hold their annual Battler Party where all the new students get to promote the Battler they joined. Sullivan looks forward to seeing Iruma-kun but while he’s at the Thirteens’ Dinner...

Sullivan is apprehended by the Demon Border Patrol on suspicions of unlawfully entering the human world. He still hopes to somehow make it to the Battler Party to see his precious Iruma-kun... Meanwhile, Iruma had no idea what was going on with Sullivan and was preparing for his presentation for the Battler Party. After going through several ideas, they decide to create things called fireworks that are supposedly from the human world and they spend the night at school to create them. And so, began the fun sleepover for the MagiApp Battler kids.

Iruma and the others continue to prepare for the Battler Party. The launchpad for the fireworks is almost complete, so Iruma goes to look for Kiriwo. Suddenly, Iruma’s ring starts dragging him and is led all over Babyls until he finds a mysterious hidden room. Kiriwo was behind those doors planning a certain project. We also find out exactly who Kiriwo had been talking to on the phone. What does Iruma find in the mysterious room?

Suddenly, all of Babyls is surrounded by invisible walls! On top of that, they are unable to get a hold of the outside and there are invisible walls that popped up all over the school. Amidst all the chaos, Kalego and the other teachers have the students take shelter in the central plaza. Since Kiriwo is missing, Iruma decides to go look for him with the help of Asmodeus and Clara. Will Iruma be able to find Kiriwo?

Kiriwo’s plan to destroy Babyls continues to move forward. Iruma somehow made it to the hidden room. Kiriwo looks completely different than what Iruma is used to, and Kiriwo proclaims that he’s going to use the fireworks that the Magic Apparatus Battler created to blow Babyls up... Kiriwo then tells Iruma about his childhood. Iruma sees the true demon side of Kiriwo. Will he be able to save Babyls from this crisis?

Part A: The ceremonies to give out the prizes for the Battler Party has now begun. Iruma and the other members of the MagiApp Battler hope to get the Grand Prize! That was also what Iruma had promised Kiriwo. Who will the prize go to? Part B: Iruma happens to stand out more after the incident with the fireworks. The head of the Demon Border Patrol, Azazel Henri, begins to suspect that Iruma may actually be human and he visits Babyls. Wait, this all seems rather familiar...

One of the most popular idols in the netherworld, Kuromu-chan, holds an all-day concert at the Makubari Dome. Dem-dols have the important job of helping demons release the stress and evil desires they feel during their Evil Cycle. Kuromu was considered a shining new star in the field, and her tickets would usually sell out in one day. But she actually had a secret that she couldn’t tell anyone... Iruma just happened to be lucky enough to get tickets for her concert and takes Asmodeus and Clara with him!

Part A: Iruma and Asmodeus encounter a rather strange girl named Valac Clara. Because of her friendly yet strange demeanor, some students seem to be taking advantage of her... Part B: Iruma had become closer to both Asmodeus and Clara. They started picking him up from his house to walk to school together and Iruma was still trying to get used to demon life. One day at lunch, some kids try to pick on Iruma, but...

Kuromu’s true identity happened to be Crocell Keroli from the Misfit Class! The more Keroli talked to Iruma, the more she became jealous about how popular he is, and she ends up collapsing. There was no way that Keroli could continue with the concert, but she had a reason she could not cancel the concert. In order to somehow still make the concert at Makubari Dome a success, Iruma and his friends do something rather surprising!

Iruma had finally started getting used to his life in the netherworld. As he continues having fun with his classmate, he begins to wonder if he should really be allowed to stay in the netherworld. Seeing that Iruma seems troubled, Asmodeus and Clara decide to cook for him. But Clara’s mother’s recipe is filled with items that even Asmodeus doesn’t know about. The two end up having a cooking competition. Which dish will Iruma choose?

Iruma obtains the Gluttonous Feeder ring which feeds upon the magical powers of others. Iruma is still doing everything he can to not stand out at school, but an incident occurs in class involving the ring, which ends up bringing even more attention to him again. Meanwhile, a certain demon was wondering if Iruma was actually human. That demon just happens to be the student council president, Azazel Ameri. But there’s a very unique reason that makes her think Iruma is human...

The one who had bumped into Iruma in the hallway was Ameri, who had been convinced that Iruma is human. When they bump into each other, Iruma finds out that Ameri has a shojo manga from the human world called “First Love Memories.” “First Love Memories” is considered forbidden texts in the netherworld. Ameri desperately wants to know what they’re saying in the manga so she asks Iruma to read the text for her, which would also prove that he’s human. Thus, began Iruma and Ameri’s live readings!

Kiriwo’s dream: To make a world where all demons would be equal, even if they didn’t have that much magical powers. Iruma completely agreed with this statement, so he proposed they shoot for the grand prize at the Battler Party. If they’re able to get the grand prize, everyone, including high-ranking demons, would see how hard Kiriwo and the Magical Apparatus Battler worked. All the Battlers are getting their presentations ready for the Battler Party on the day of the Party Eve. But suddenly, the fireworks shell that Iruma and others prepared suddenly goes missing...

Part A: When Iruma woke up, most of the ruckus was already over. Sullivan tells Iruma that Kiriwo had been arrested. What happened when the giant fireworks went off? Part B: The ordeal at Babyls comes to an end. The Battler Party is finally about to start! The students all do their best in order to get the Grand Prize, and the students' families come by to enjoy the festivities!