The demon king is none other than Derkila of the demon world.
We understand your curiosity for the demon king Derkila, as he opposes such a mysterious figure who is only mentioned or shown once or twice during a full season.
Derkila, besides the fact that he was the Demon King a few hundred years ago but has now mysteriously disappeared, was also a great leader for being able to build a cozy atmosphere in the demon world. Intriguingly, the enigmatic and elusive Demon King Derkila had forged close bonds with some of his subordinates, most notably with the young Sullivan, who served as his loyal subordinate before his mysterious disappearance.
Sullivan and Derkila’s Relationship
In season 2, episode 21, it is revealed that Sullivan and Derkila shared a deep bond and were inseparable during their time together. Sullivan often reminisces about their shared experiences while Amduscias Poro, another one of Derkila’s subordinates, verifies their closeness. Other members of the Thirteen Crowns, a group of loyal followers, were also among those who served Derkila dutifully.

Who Is Amduscias Poro?
WARNING: The following text contains spoilers for those who have not read the manga.
Poro, tiled as the “Legendary Sound Demon,” was one of the most devoted servants of the former demon king Derkila. His impressive title was earned by his incredible feat of stalling an entire army for a whopping 666 hours using his music. In the manga, Poro’s character is set to make a major appearance as a guest judge for the first-year music festival presentation for the upcoming season 4.
Poro and Derkila’s Relationship
As his title suggests, Poro has an undying passion for music and spent many hours playing with Derkila in the Royal One. Interestingly, Poro mentions that Derkila had no musical talent.
Although it is unclear how Derkila feels about Poro, it is evident that Poro holds a deep love and admiration for his former master. He often reminisces about their time together and expresses his longing to see Derkila once again. Despite Derkila’s mysterious disappearance, Poro’s loyalty to him remains steadfast, and he would do anything to be reunited with his former master.

The Legend of Derkila
Chapter 205 of the manga reveals an intriguing tale about Derkila, shared by none other than Sabnock. According to Sabnock, one of his favorite myths and legends about the Demon King tells of an incident where Derkila stopped a raging war at Death Square. The tale describes how Derkila, in an incredible display of bravery, caught every weapon thrown in the battle with his own body, preventing any demon from being harmed except for himself.
Sabnock further speculated that perhaps the reason why Derkila caught every weapon with his own body was to understand and feel the pain that the war created. By experiencing the pain firsthand, Derkila would be the only one worthy of ending the conflict.
Why Did Derkila Disappear?
The disappearance of the Demon King Derkila has captivated fans of the series, who are eager to learn more about what happened to him and where he might be. Despite being mentioned in both the anime and manga, the reason for his disappearance remains unclear.

While we have seen glimpses of Derkila in Sullivan’s flashback in season 2, episode 21, and during Iruma’s legendary leaf blooming ceremony in season 3, episode 17, where Iruma and his friends are performing the “Kuan Kuan” spell when suddenly a shadow in the shape of wings wraps around Iruma’s body. Within this shadow, Derkila suddenly appears on Iruma’s back and utters the words, “So you’re the one.” This encounter is short-lived, as Iruma soon opens his eyes and returns to reality.
The ongoing anime and manga have heightened the level of suspense surrounding the mysterious disappearance of the Demon King Derkila. Fans are left to ponder the fate of such a powerful and imposing character, wondering what could have happened to him. However, it seems that the reveal of Derkila’s fate may still be some time away, possibly until the near end of the manga.
Read more: Why Did Sullivan Adopt Iruma in Welcome to Demon School, Iruma-Kun?

Derkila’s Personality
In the final episode of the second season of Welcome to Demon School, Iruma-kun, fans were given a rare glimpse into the personality of the Demon King Derkila through Sullivan’s recollection of his past. The flashback scene revealed a laid-back and easygoing side to Derkila’s character.
Despite having a scheduled meeting with the Thirteen Crowns, Derkila was found lounging and relaxing at the top of a cliff, showing a carefree attitude that was unexpected for someone in such a high position of power.
Derkila is depicted as being annoyed by the meeting with the thirteen crowns, which he views as treating the Netherworld as a mere object to be played with. Iruma himself comments on Derkila’s interesting personality and how enjoyable it would have been to spend time with him, to which Sullivan readily concurs.

In addition to his easygoing and teasing personality, Derkila also appears to be a very charismatic leader. This is evidenced by the fact that he was able to unite the demon world and create a sense of community among his followers. Under his leadership, the Netherworld became a place where demons could live comfortably and coexist peacefully. This is no small feat, considering the often competitive and cutthroat nature of demon society.
Furthermore, Derkila’s pride and admiration for what he had built and his desire to protect it are evident in his actions and interactions with his subordinates. It is clear that he saw the demon world as more than just a place to rule – it was his home, and he wanted to make it a welcoming and thriving place for all who lived there.
Despite his disappearance, Derkila’s legacy lives on in the demon world. His leadership and vision have undoubtedly left a lasting impact on the demon world, and his memory continues to inspire and influence those who knew him.

What Does It Take To Be the Demon King in the Netherworld?
In the climactic finale of season 2 of Welcome to Demon School, Iruma-kun, viewers were left on the edge of their seats as the main characters, Iruma and Sullivan, found themselves seated on a bench in the bustling Magical Street. As they sat there, taking in the sights and sounds of the lively city, Iruma couldn’t help but feel a sense of curiosity and intrigue. He turned to his grandpa, Sullivan, and posed a question that had been weighing on his mind: why didn’t Sullivan want to become the new demon king, despite his obvious qualifications?
As the two engaged in a deep and thoughtful conversation, Iruma learned that the path to becoming the demon king was not an easy one. Sullivan shared with him the grueling process one must endure in order to ascend to the throne, a journey filled with obstacles, challenges, and difficult decisions. Despite being fully qualified for the position, Sullivan had chosen to pursue a different path, one that aligned more closely with his personal values and desires – and that is to take care of his beloved grandson, Iruma.
Sullivan’s explanation of the process of becoming a demon king was nothing short of fascinating. According to Sullivan, the Thirteen Crowns were a vital component of the demon king’s rule. These individuals had been entrusted with specific duties that were critical to the smooth operation of the Netherworld. From maintaining the balance of power to overseeing the economy and managing relations with other worlds, the Thirteen Crowns were the backbone of the demon king’s administration.

However, gaining the trust of each of the Thirteen Crowns was no easy feat. As Sullivan explained, becoming the demon king required a unique combination of strength, skills, attitude, and relationships. A potential candidate had to prove their worth through years of hard work, dedication, and service to the Netherworld. They had to demonstrate that they were capable of handling the immense responsibility of the throne and that they were committed to the greater good of demon society.
Moreover, the process of becoming the demon king was not just about winning the trust of the Thirteen Crowns. It also required the support of the demon population as a whole. As Sullivan continued to delve deeper into the intricacies of demon society and the responsibilities of the demon king, Iruma could feel his mind expanding with each passing moment. He couldn’t believe just how much he had yet to learn about this strange and fascinating world.
Sullivan went on to explain that the role of the demon king was not just about gaining the trust of the Thirteen Crowns and the demon population. It was also about taking on a level of responsibility that few could even imagine. The demon king was the embodiment of the Netherworld itself, and as such, he had absolute power and authority over all that resided within it.

Sullivan emphasized the weight of the demon king’s words, explaining that even if a task seemed impossible, the demons were obligated to obey his orders without question. If the demon king commanded them to go straight, even if there was no path ahead, they would do so, forging their way forward through sheer force of will and determination.
But despite the immense power and responsibility that came with the role, Sullivan confessed that he wasn’t sure if he was truly cut out to be the demon king. He spoke with a sense of humility and self-doubt, acknowledging that even if he were to ascend to the throne, he doubted that he could ever be as amazing as the former demon king, Derkila.
Read more: Does Iruma Become the Demon King?