To summarize, Sullivan’s decision to adopt Iruma was primarily driven by his feelings of loneliness and envy, which arose from the fact that he did not have any family or loved ones of his own.
Moments between Sullivan and Iruma in Welcome to Demon School, Iruma-Kun has emerged as our favorite. We get to see a weird dynamic between an old powerful demon and our young and sweet human protagonist.
In this article, we will delve deeper into the relationship between Iruma and Sullivan, focusing mainly on the events of season 1. It’s safe to assume that if you’re a die-hard fan like us, you’ve probably already indulged in every episode and chapter. However, for those who haven’t had the pleasure yet, we strongly suggest that you join in on the fun and witness the adorable moments between these two characters for yourself!

How Did Sullivan Adopt Iruma?
To put it differently, it can be said that Sullivan didn’t technically adopt Iruma – it was more of a kidnapping scenario.
The story begins in the first episode, where we are introduced to Suzuki Iruma, a 14-year-old boy who is forced to work on a fishing boat due to his useless parents (this is how the anime describes it, not our words!). During a storm at sea, the fish cages break open, and Iruma tries to hold the doors closed. However, he eventually loses his grip, and the fish start falling on top of him. Suddenly, time seems to stop, and the fish stop falling.
In the blink of an eye, Iruma finds himself tightly bound by a rope while a tall and slim demon looks at him. The demon places a paper tag on Iruma’s chest with the word “sold” written on it. In the next scene, the two of them are transported to the Netherworld, with the demon holding Iruma captive. He then casts a spell on Iruma, which allows him to understand the language of demons.

Iruma is understandably shocked and demands to know what’s happening. The demon explains that they are in the Netherworld, the world of demons, and that Iruma’s soul has been sold by his parents. The demon introduces himself as Sullivan, leaving Iruma to come to terms with the fact that he is being held captive by a real-life demon.
As he starts to ask how this could have happened, Iruma’s thoughts interrupt him, recognizing that it’s something his parents might have done. He realizes that human desires, whether for money, power, or love, are never-ending and can be considered “unsightly desires.” These desires can lead people to sell their souls to demons.
Iruma’s father had told him that he could live independently as soon as he learned to walk at just one year old and then went on to focus on fishing.

After being taken to a mansion by Sullivan, Iruma suddenly finds himself wearing a bib like a baby and sitting on a large chair while Sullivan kneels before him and asks, “Will you be my grandson?”
Sullivan further explains that he is actually single but has always longed for grandchildren. He admits to feeling envious of Lady Levi and Belial, who boast about their own grandchildren and how they spoil them. – we’ll get to who these are later in this article
Iruma questions whether he really has a choice since he has already been sold, but Sullivan assures him that he will respect his wishes. Iruma begins to worry because he has NEVER declined anything in his life.

Sullivan starts to cry and pleads with Iruma to take him as his grandfather, saying that it would be like helping an older man in his final days. Overwhelmed by Sullivan’s emotions, Iruma signs a contract to become the demon’s grandson.
In a comical scene, a potato-like animation of Sullivan is shown dancing gleefully with the contract in his hands while Iruma looks down with a sense of regret on his face.
Now that everything is done, Iruma is officially the grandchild of the great and powerful Sullivan. He transforms the room into a lavish and luxurious space and assures Iruma that now that he is his grandson, he will be taken care of with guaranteed provisions for food, clothing, shelter, and education.

Why Did Sullivan Chose Iruma to Be His Grandchild?
In the first chapter of the manga, the narrator introduces Iruma as a kind-hearted boy who is always willing to help others, regardless of whether or not they ask for his assistance. He never complains, even when faced with unreasonable requests. Iruma is even amazed at how he became such a good-hearted person.
This is one of the reasons why Sullivan chose Iruma to be his grandchild, as he is just as pure as an angel. Sullivan notes that Iruma doesn’t even have the habit of getting angry with anyone, not even his bad parents.

Sullivan also takes advantage of Iruma’s tendency never to decline requests. He frequently uses words such as “please,” “help me,” and “I beg of you” in order to get Iruma to be his grandchild.
Despite spoiling Iruma, Sullivan does set clear boundaries to help him grow as a person and adapt to his new life.
Ultimately, Sullivan chose Iruma as his grandson because of his kind-hearted nature, which is a rare trait not only among demons but also among humans.
Read more: Welcome to Demon School! Iruma-kun Season 3 Trailer Released

Does Sullivan Love Iruma?
Sullivan loves Iruma so much that the first time Iruma calls him grandpa, he is filled with immense joy and ecstasy. However, Sullivan also joked that if Iruma had declined to be his grandson, he would have eaten him for dinner.
Such is the depth of his affection for Iruma that he goes to great lengths to ensure his safety, even spraying him with demonic essence to prevent other demons from eating him.
On Iruma’s first day at school, Sullivan is proud and happy to walk him to the entrance ceremony. He finds Iruma cute in his school uniform and is excited to take a picture of him next to the school entrance sign.

It’s not until Iruma’s first day at school that he discovers Sullivan is actually the principal of the school. During his speech at the ceremony, Sullivan excitedly shouts out, “Iruma! It’s grandpa~!” and waves his hands in front of the entire school, showing how proud he is to have a grandson, even though their relationship began on the same day Sullivan kidnapped Iruma.
Sullivan proceeds to announce to the entire school that his grandson, Iruma, has also enrolled and expresses how cute he is. He not only mentions Iruma’s name but also shows the entire school the picture they took together next to the school entrance sign and promises to give copies of the photo to everyone.

During Iruma’s speech as a school scholar, Sullivan is seen taking a video of him, showing his pride and support for his grandson. After the speech, Sullivan gives Iruma a note with a cute message written on it: “I hope these words of mine will help you overcome any hardship in your school life.”
At the end of the chapter, Iruma gains recognition in the school newspaper for “defeating” the top-ranking student, Asmodeus. Sullivan is thrilled when he sees the newspaper, proudly exclaiming, “That’s my grandson! Iruma-kun, a great future awaits you.
As the series progresses, it becomes evident that Sullivan loves Iruma deeply and spoils him with everything he needs, including delicious foods that he never got to experience in the human world.

In episode 2, Sullivan wakes Iruma up with the endearing phrase, “Good morning, my precious grandson!” Then during breakfast, Sullivan presents Iruma with a stash of new uniforms, books, and gifts to celebrate his first day of school. He even reveals that he made an embroidered handkerchief for Iruma, which is why he had bandages on his hands. Sullivan explains that although he found embroidery tiring and was not used to it, he had fun making it for his grandson.
Opera attempts to intervene and stop Sullivan when he goes too far, such as stalking Iruma at school. However, Sullivan consistently goes above and beyond for Iruma, fulfilling all of his requests whenever possible, such as placing him in the same class as his friends.

In episode 5, when Kalego almost cuts off Iruma’s hand for possessing the powerful ring of Solomon, the ring of gluttony, Sullivan appears out of nowhere to stop Kalego. He becomes angry with Kalego for endangering his grandson.
When Iruma asks Sullivan to train him for the Rank Advancement Test: Execution Ball Canon, saying “I’ll be in your care! Mr. Headmaster!” Sullivan responds by saying, “It’s grandpa <3 outside of school, isn’t that right!” and proceeds to train Iruma despite his busy schedule. Sullivan always finds time for Iruma and even reinforces his hands with magic after the training so that he can catch a ball thrown by a demon, ensuring fair competition despite Iruma being just a human.
After thanking Sullivan for his training with a cute smile, Sullivan embraces himself and exclaims that he will save Iruma’s smile in his heart’s memory. From then on, he passes Iruma on to Opera for further training.

After the test, Iruma returns home to announce his good news, and Sullivan and Opera greet him at the door. Iruma tells them about his rank advancement, and Sullivan begins to celebrate. However, he becomes jealous when Iruma thanks Opera instead of him and starts to cry, thinking it’s unfair. Iruma then thanks Sullivan as well.
In this episode, the three excellencies – Beliard, Lady Levi, and Sullivan – have a meeting to discuss the next demon king. Despite their status as powerful beings, they do not adhere to the dark and serious demeanor typically associated with demons. Instead, they discuss their grandchildren, exchanging pictures and describing how great they are.
Typically, it’s just Lady Levi and Beliard discussing their grandchildren, but Sullivan surprises them by announcing that he also has a cute grandchild. The two are confused since Sullivan doesn’t have children, but he gives them pictures of Iruma, and they agree that he is cute. Lady Levi jokes that it was probably a kidnapping, but Sullivan just chuckles and says, “no comment.”

Afterward, the three finally had a serious meeting to discuss who the next demon king should be. Lady Levi and Beliard suggest that Sullivan would be the best fit, but Sullivan surprises them with a touching speech:
This is my first time having a grandson, and I want to coddle him lots. I just take my eyes off him for a moment, and he’s grown up. Really… It’s fun watching over a child’s growth. I have no intention of quitting the position of headmaster!
He even admits that he doesn’t consider being a demon king because it would take him away from watching over Iruma. With his touching speech, Lady Levi and Beliard agree that the demon king’s throne can wait.

Later on, Anri suddenly opens the door to their meeting and accuses Sullivan respectfully of illegally traveling to the human world. This accusation reveals that Sullivan was willing to take risks for Iruma from the very start, as he allowed himself to be summoned to the human world by a pair of humans. Despite their different species and lack of blood relation, Sullivan became very attached to Iruma.
When he was under warrant for questioning, Sullivan contacted Opera to ask about Iruma’s well-being. He was worried that Iruma might be having difficulty because of his concern for his grandpa. However, Iruma was simply playing a game and had no idea about Sullivan’s arrest. This news broke Sullivan’s heart, but he still asked Opera to take care of Iruma and read him a bedtime story. He even added, “Let Iruma-kun know I love him while I’m away~!” Sullivan’s love and affection for Iruma were apparent, even in his difficult situation.

Continuing to episode 19, Iruma uses a powerful spell called “Pandora” while Sullivan is still being interrogated. Sullivan explains in the previous episodes to Iruma that the spell should only be used in critical situations. When Sullivan receives an alert that Iruma used the spell, he ignores Anri’s men and flies off to Iruma. However, in episode 20, it is revealed that Anri actually tried to stop Sullivan from leaving, saying that the investigation is not yet complete and that he needs to stay until the suspicions are cleared. Sullivan counters this by saying they don’t have any evidence, and when Anri persists, Sullivan shows his true demonic side.
Sullivan gives Anri a firm look and tells him that he is going back because he promised Iruma that he would return to him. His face becomes serious, and his demonic features are visible, causing Anri to freeze in place, unable to speak, as if he is trapped in Sullivan’s powerful energy.

Going back to the beginning of episode 19, Iruma is lying on Sullivan’s lap when Sullivan captures the main antagonist of the season. He then carries Iruma on his back and shows him his demon friends, who are waiting for him after they successfully defeat Amy Kirio. Iruma is overjoyed at sight. In the end, we see Sullivan carrying Iruma on his back as he sleeps after their exhausting day.
Read more: 13 Interesting Facts About Welcome to Demon School, Iruma-Kun You Probably Didn’t Know