The story begins with the introduction of Suzukui Iruma, a 14 year old boy. He is described as being very kind-hearted, and unable to deny anyone a single request, regardless of how difficult or ridiculous it is. However, because of this, he often finds himself in dangerous situations, and lives a difficult life.
Growing up, Iruma found himself in dangerous situation after dangerous situation, as his parents are selfish, mean people with little to no common sense whatsoever. However, they finally cross the line when they accidentally summon Lord Sullivan, a demon, and sell their son in exchange for money and wealth.
After being sold, Iruma fears for his life, until the demon presents him with expensive food and clothes, and explains the real reason he bought him. Lord Sullivan explains that he never got married or had children, but desperately wants a grandson, because his friends always boast about their grandchildren. Iruma tries to refuse, but is swayed by
Sullivan's begging, and agrees, stamping a contract. Sullivan hints that, if Iruma had refused, he may have simply eaten him instead.
Lord Sullivan declares that he will spoil Iruma and provide him with the best of everything. However, that also means that he will have to go to school, especially since Iruma never had time for proper study after living such a difficult life, and dragged around by his selfish parents. Iruma is given a uniform (his standard outfit) and enrolled at Barbirus Demon School; he learns that he is the first human to enrol, and that he has to keep his real identity secret, lest he be eaten by demons.
Iruma arrives at orientation at learns that Lord Sullivan is, in fact, the Principal of the demon school. In his pride for his grandson, Lord Sullivan boasts about him on stage, to Iruma's horror, and even presents a poster. He then removes the Freshman representative, Asmodeus Alice, from the stage and declares that Iruma will instead make the speech.
Iruma's terrified demeanor is mistaken for confidence by the students; once on stage, he decides to read the words prepared for him on a piece of paper on the podium, in lieu of a speech. This causes an uproar, and it is revealed it was a forbidden spell that would have blown his limbs off if mispronounced. It is revealed that the effect of the spell is that he will not fall at all, no matter what, for the entire day.
The freshman representative challenges Iruma to a duel immediately after the orientation and summons the student body to watch the fight. Due to his difficult and crazy life, however, it is revealed that Iruma can dodge anything, and has "0 attack, infinity defense. For better or worse, a completely harmless person." Iruma dodges Asmodeus' fire magic for 20 minutes, before tackling him to save a nearby student. The effects of the spell from earlier activate to stop him falling, and Iruma defeats Asmodeus in an accidental German suplex.
Iruma becomes the most talked about 'demon' in the school, and later Asmdeous arrives to congratulate Iruma on his victory. As per demon custom, he now follows Iruma and serves under him. He swears they will dominate the school together, to Iruma's surprise.
Iruma begins his first day at school, and attempts to tell Lord Sullivan that he doesn't want to go to Demon School because he's scared of being eaten. He is unable to, however, as he is showered in gifts and praise, and feels too bad ruining such a happy atmosphere. The demon servant, Opera, is passively introduced in the background, bringing gifts.
Attending school, he is greeted cheerfully by Asmodeus, and told the first lesson of the day was summoning a familiar, and that a students rank will be determining by measuring its strength.
Naberius Callego enters, and announces himself the teacher of the class, and quickly explains how to summon a familiar, including that a familiar cannot harm its master. He makes it clear that he believes Iruma is relying on the favoritism of his 'grandpa', the principal.
Asmodeus summons his familiar, a Gorgon Snake, while Callego broods over how Iruma and Lord Sullivan act so similar, and how Lord Sullivan has been treating him unfairly. He plots to expel Iruma the moment he makes any mistake in the summoning ceremony as revenge. Unknown to him, Iruma also plans to mess up the summoning due to his lack of magic, and hopefully get himself expelled without confrontation.
However, as the summoning ceremony for a demon summoning a familiar and a human summoning a demon for contract are the same, Iruma accidentally summons his teacher, Naberius Callego, and forms a contract, turning him into a tiny chick.
Later, Lord Sullivan reveals the contract will last for 1 year, and ending it prematurely will cause both of them to die.
Iruma becomes more notorious as rumors of him enslaving a teacher as a familiar
Iruma and Asmodeus are walking down the hallway after collecting their class lists and materials for the year, when a demon rolls past them at speed, crashing into a pillar, and destroying it. Iruma is concerned, and goes to check on them, meeting Clara Valac. Asmodeus issues a warning not to talk to her, that goes unheeded.
Clara is unharmed and delighted to have a new person to play with, startling Iruma with her enthusiasm. She introduces her right foot as Connor, and her left foot as Murph, before enthusiastically inviting Iruma to watch her crash into more columns.
Asmodeus explains that Clara is another 'weirdo', and that people avoid her because she will get them into trouble. However, Iruma finds himself dragged into her antics immediately, unable to refuse and swept along with her fast pace. The three play house for two hours straight, leaving the two boys exhausted. Clara offers them snacks and drinks, and introduces her inherited magic; she can create anything she's ever seen before.
Iruma (and Asmodeus, reluctantly) continue playing with her for several more days. Clara seems extremely happy, humming and laughing as she goes to meet with her new friends every day.
On the way there, Clara overhears several demons sitting on some stairs. It is revealed that some demons take advantage of her power, extorting drinks and other items from Clara in exchange for their 'friendship'. Though Clara is rather ditzy in nature, she admits to herself while walking away that she knows that, without her power, people wouldn't bother playing with her.
Once she meets up with Iruma, she begins to shower him with snacks, drinks, and whatever she can conjure, saying "You can have them all!
I'll give you anything you want! So please, keep playing with me...". Iruma quickly refuses the gifts and apologizes. Clara, panicking, begins to cry. She explains that the snacks are her 'nuisance fee' and that Iruma would leave her like everyone else, now that he's bored. Iruma explains that he doesn't need the snacks, and that he'll keep playing with her anyway, because playing with Clara is fun. He explains that Clara does go overboard sometimes, but that's because he's not used to playing. Clara begins to laugh and cry, happy someone wants to continue playing with her even without being bribed.
The demons from the stairs suddenly appear, demanding drinks from Clara, sneering. Clara instead conjures an entire vending machine, crushing the leading demon beneath it, telling them to insert some coins if they want anything.
Iruma covertly asks Asmodeus to make sure no one else will take advantage of Clara again, which he does so (though the bloodstains on his coat contradict his assertion that the
Asmodeus and Clara come to pick up Iruma in the morning on their way to school. Lord Sullivan comments that he's happy that Iruma has managed to make two new friends so quickly. Iruma freezes, initially denying being friends, and even questioning if demons and humans can even be friends to begin with. It is also revealed that Iruma has never made a friend before, and doesn't know how one should go about making them.
Iruma continues to stress about the philosophy of friendship over lunch, where the menu board is explained. Students can order food for free, and the quality you can order depends on your rank. There is also a shop with better quality food and items for sale in the cafeteria. Someone attempts to play a mean prank on the three, ordering enough food for 50 people and sending it to Iruma and co.'s table. Asmodeus is furious, and turns to tell Iruma to send the food back, only to realize that somehow, Iruma had eaten all of it. In addition, he asks for more, and a waiter exclaims that the chef had fainted, presumably under the stress of making so much food.
A commotion occurs, where the shop owner, Camu Camu, attempts to arrest Clara. He is very focused on preventing shoplifting, and not losing money, and considers Clara's ability to be 'the ability to shoplift, just by looking', as she can replicate anything she sees inside. He tells her repeatedly that she is banned from the shop, but Clara believes that they are playing. Camu Camu warns that anyone who shoplifts from his store will be pieced by his spear.
Naberius Callego enters the cafeteria, back from his vacation. He demands to know what the ruckus is, before spotting Iruma. He growls, and warns Iruma that he'll never be his familar, and that if Iruma thinks he can chain him up, he'll kill him. He suddenly spots Clara standing next to Asmodeus and Iruma and notes with fear that their numbers have increased. Clara rushes forward, introducing herself and rambling about her friends, and attempting to give him chocolate. Callego panics, realizing she is the hardest type for him to handle, and attempts to flee.
Clara grabs on to him, and instructs Iruma to put a nearby seal on his hand, which turns Callego back into his chick form, which Clara attempts to catch. Camu Camu attacks all of them, causing Iruma, Clara and Asmodeus to flee, leaving Callego to pay for the seal in his chick form, as it was apparently taken from the shop.
Iruma realizes how much fun he has with Clara and Asmodeus, and asks them nervously if they want to be his friends. They express confusion at first, as friendship is apparently not a concept in the Demon World, but once Iruma explains, they readily agree. Iruma then declares they are his Number 1 and Number 2 friends, which Clara and Asmodeus begin to bicker over.
At the end of the chapter, Iruma and co. are apparently placed in the 'abnormal class' by Lord Sul
One day, Iruma offhandedly mentions that he doesn't want to be noticed at school anymore to his demonic guardian Lord Sullivan. This leads to the creation of the 'Abnormal Class' - a class for strange students, who like to attract attention, so that Iruma can blend in.
Iruma arrives alongside his friends, Asmodeus and Clara, outside a massive classroom door. He opens the door, only to find a number of deadly weapons flying right for his face. Iruma stumbles into the classroom, somehow dodging every single one of the dozens of deadly weapons being aimed his way. He receives a round of applause, and finds that the class was making bets on the number of weapons new students would be impaled with upon entering the classroom. Iruma was the only one to dodge every weapon.
He soon learns of a student even stranger than most of the abnormal class - a demon who refused to dodge a single weapon, taking them all head on in a show of strength. Sabnock Sublo is introduced, with swords sticking out of his body. He declares that he is the most suitable candidate for the role of Demon King, a dream he will achieve by reaching rank Yod. The Demon Ranking System is introduced, with Yod being the topmost rank, and Aleph the lowest. Sabnock also mentions that the quickest way to the top was to defeat strong opponents. He confronts Iruma, and questions Iruma's status as a genuine demon, before Asmodeus steps in. The two argue, with Asmodeus declaring his position as Iruma's friend.
Before it can escalate, the teacher - revealed to be Callego - arrives, and instructs everyone outside for the very first ranking test. The test is a race through Saezuri Valley - full of countless huge mountains. They are banned from entering Kanakiri valley, as they did not receive permission to enter. Sabnock declares that he will conquer Karakiri valley regardless, to which Callego replies that he does not care.
The signal to begin the race happens as Callego - along with the rest of the student body - suddenly grow wings, leaving Iruma panicked and h
The class takes off, leaving Iruma teetering at the edge of a cliff. He wavers, but keeps his balance until he is suddenly kicked over the edge by Callego.
Most of the class is taking the race leisurely, and Callego despairs at the lack of motivation. The exception is Asmodeus - who speeds ahead. He quickly realizes he has a hitchhiker, however, and finds Clara sitting on his back. The two quabble, as in the distance Sabnock speeds towards Karakiri valley.
Sabnock smashes his way through Karakiri valley, satisfied with his decision. The valley is much harder to traverse but a much shorter route. He notes he's making record time. Callego, watching through a tv, crosses Sabnock's name off a list, pondering whether the demon would be lucky enough to escape with just a few broken limbs.
Meanwhile, Iruma is caught in the beak of a giant demonic bird. He was caught after falling off the cliff. He is deposited into a gigantic nest, where he is attacked by a gigantic chick, which attempts to eat him. While being chased, Iruma notices the chick collapsing behind him. He investigates and finds a gash on the monster's leg. He quickly resolves to help, and grabs a stone shard. He quickly cuts his hand, and shows it to the monster, before bandaging it. The monster understands, offering the injured leg. Before he can bandage it, however, Iruma's blood drips into the wound, healing it to the shock of both parties. The monster tests its leg by standing, and Iruma smiles in relief. Disregarding its initial plan to eat him, the monster nuzzles up close in thanks, before indicating for Iruma to climb on his back.
Alone and bloody, Sabnock stares down the King of Karakiri Valley in despair.
Chapter 7 - The Person to Become the Demon King
Sabnock reminisces about his time as a child, reading up on Prophecy of the Demon King, while fighting the King of the Valley. It was revealed that he was raised by his family to be the next Demon King. However, that is not the true reason why he wants to be the Demon King. The true reason?
"Because the Demon King is the coolest!"
Sabnock reveals his inherited magic - the ability to create a weapon from any material he bites, which then eats away at everything. However it is not enough, and he lays defeated in front of the King, declaring that he didn't regret anything since he always followed his own will. At the last moment, Iruma appears from above, throwing himself in front of Sabnock. Right as the King's claw is about to reach Iruma, it pauses, as the monster Iruma helped hovers in front of it. Sabnock reveals that this is the chick belonging to the King of the Valley, and prepares to take advantage of the distraction to launch a devastating blow.
Instead, Iruma signals to the King, waving and telling him that the chick's leg was all healed. He convinced Sabnock to lower his weapons as well. The leader bows, thanking them to Sabnock's shock. He thinks to himself that Iruma is someone special.
Once the race is over, the Ranking Owl is introduced. Though Iruma and Sabnock made it back with the help of the King, they didn't make it back in time, and were disqualified. Sabnock thanks Iruma for saving him, and declares Iruma his rival. One by one, students reach into the Ranking Owls' feather and pull out a ranking badge. Eventually it is Iruma's turn. He reaches into the owl, but it screeches and flies away without giving him a badge.
A flashback once again from Sabnock's childhood interrupts the scene, and reveals the 'Demon King's Prophecy.'
"All demon lineage, far and wide
Bound by the blood contract
All creation shall be blessed
By the one who swoops down from foreign land
On their right hand
A golden light is kept
It is the light of Solomon's ring."
The scene returns to reveal Iruma, with a strange golden ring on his right hand.