YES! Ameri knows about Iruma’s secret and she found it out way back in season 1, episode 6 of Welcome to Demon School, Iruma-kun!
In episode 6 of season 1, Ameri Azazel expresses her unwavering belief in the existence of humans, and her conviction stems from a closely guarded secret that she possesses. Ameri’s family has passed down prized articles for generations that serve as concrete proof of the existence of humans. These coveted items are referred to as the “forbidden books,” which document various aspects of the human world, and funny enough, it’s actually… Manga!
Interestingly, Ameri’s favorite genre of these “forbidden books” is shoujo manga, which she adores despite her inability to comprehend human letters. Despite this, Ameri cherishes these books for her love of reading charming and relatable high school romance scenes — the downside, though, is that she can’t understand human letters.

But going back, Ameri is already doubtful of Iruma’s true nature as a human due to several reasons, which include:
- Iruma’s use of forbidden spells
- Alice, the top student, submitted to Iruma
- Iruma’s ability to summon a demon
- Iruma’s immeasurable rank of power
- Iruma’s magic-accumulating ring caused chaos in the classroom
- Iruma’s creation of a tree that is unknown in the demon world
- Ameri’s knowledge and belief in the existence of humans
These were the reasons why Ameri was already suspicious of Iruma’s true nature as a human, but her doubts were ultimately confirmed during an encounter with him.

Ameri accidentally bumped into Iruma, and at that moment, she felt like she was in one of the books she had been reading. Her initial thought was that Iruma was using his human charm to make her fall in love with him, but this turned out to be far from the truth. After Ameri regained her composure, she and Iruma found themselves in an awkward position, which caused Ameri’s manga to fall. Iruma picked it up and exclaimed with delight, “So nostalgic! This is ‘First Love Memory!’ I used to read this every week.” This comment from Iruma gave Ameri the confirmation she needed to know that he was indeed human.
However, Ameri’s certainty was short-lived when she noticed that Iruma could understand the book just as she couldn’t. While Iruma was taken aback by his own words, fearing that he may have inadvertently exposed his human identity to Ameri. The thought of being discovered and ostracized by the demon world made him anxious and scared. But, to his surprise, Ameri asked him if he could read the book for her, which was one of Iruma’s greatest weaknesses; Iruma had always been eager to take on any task or request that was asked of him. This was a significant turning point in their relationship and marked the beginning of their friendship.
Who Knows That Iruma Is Human?

Lord Sullivan
One of the few characters who knows that Iruma is human is Lord Sullivan. From the beginning, Sullivan had adopted Iruma, knowing that he was a human. Initially, Iruma was kidnapped to the demon world, but he eventually accepted Sullivan’s offer to be his grandson since he couldn’t refuse. The reason why Sullivan picked a human as his grandson remains a mystery, but many characters speculate that it may be due to Iruma’s pure-hearted nature.
Throughout the series, Lord Sullivan acts as a mentor and guide to Iruma, teaching him about the demon world and helping him to develop his powers and skills. Despite their unconventional relationship, it has grown into a genuine bond of affection and respect. Iruma sees Sullivan as a grandpa figure and values his guidance and wisdom.
Opera
As a security demon in Sullivan’s employ, Opera would have access to information regarding Sullivan’s whereabouts and decisions. This is likely how Opera became aware of Sullivan’s decision to take home a human boy. Initially, when Sullivan brought Iruma to his mansion, Opera was hesitant and raised concerns about the decision. They suggested that there were plenty of demon foster kids available and questioned why Sullivan would choose a human as his grandson. However, Sullivan remained resolute in his decision and told Opera that they would understand soon enough. Eventually, after getting to know Iruma and witnessing his angel-like personality, Opera came to understand and appreciate Sullivan’s choice.
Read more: Is Opera a Girl or a Boy in Welcome to Demon School, Iruma-Kun?

Balam Shichiro
Balam is another character who discovers Iruma’s secret that he is a human. In episode 10 of season 2, Balam substitutes for Dali while he is on break due to his Evil Cycle. During a class discussion on demons having wings to escape danger, Balam felt Iruma’s back and realized he did not have any wings. This caused him to panic and pick up Iruma, bringing him to the teacher’s office and informing the teachers that Iruma did not have wings. However, when they checked, they found that Iruma only had tiny wings on his back (but this was actually Ali attached to Iruma’s back to save him), which caused everyone to laugh and assume that he just had undeveloped wings.
Feeling guilty about exposing Iruma’s supposed malformity, Balam apologized, and the two of them began to develop a friendship. Balam showed Iruma his scarred face and revealed his love for all things cute, which made Iruma understand Balam better. This caused Iruma to reveal his secret that he was actually a human. Upon learning that Iruma is a human, Balam is taken aback and instinctively warns him not to disclose this information to anyone else, as it could put him in danger. However, Balam’s initial shock quickly turns into fascination and curiosity about Iruma being a human. He accepts Iruma for who he is and shows no ill will towards him after discovering his secret, which ultimately strengthens their friendship.

Barbatos Bachiko
In the exciting and dramatic last episode of season 3, viewers witness Sullivan’s gratitude towards Bachiko for her exceptional teaching skills, which helped Iruma achieve the rank of Dalet during the harvest festival. As a gesture of appreciation, Sullivan invites Bachiko to his home, where she is treated to a sumptuous meal. However, the real surprise comes when Sullivan casts a powerful “Perfect Speak: eavesdropping prevention” spell, ensuring their privacy during their conversation.
During their conversation, Sullivan explains that during uneasy times in the Netherworld, educators must focus on educating to impart more knowledge to the students. He then adds, “Please continue being the special instructor for my grandson, okay?” and Bachiko just happily says, “yes!” Sullivan then drops a bombshell on Bachiko, stating that Iruma is human. Bahicko just unknowingly says “yes!” again but later realizes what Sullivan said, and as the realization dawns on her, she is left in a state of shock, unable to comprehend the full implications of this revelation.

Opera confirms that only Sullivan, Opera, Balam, and herself know about Iruma’s secret. Sullivan then poses a crucial question to Bachiko – whether she would like her memory to be erased or join forces with him to protect Iruma. Bachiko is taken aback by the gravity of Sullivan’s question and takes some time to reflect on her decision. However, before she can respond, Iruma walks into the room. She then comments that being human suits Iruma and that he is the only person who could be her student precisely because he’s not a demon. Bachiko ultimately accepts Iruma for who he is and agrees to protect him alongside Sullivan.
Azazel Henri
The knowledge of Iruma’s humanity is not widely known in the Netherworld. However, there is one person who is suspicious – Henri, Ameri’s father. In season 1, episode 20, Henri became aware that Sullivan had broken the code of conduct by visiting the human realm. Although he did not have concrete evidence, he took Sullivan into custody, hoping to get a confession. But Sullivan remained tight-lipped, leaving Henri with unanswered questions.
As Henri contemplated his suspicions, he decided to approach Iruma directly. In a private conversation, he revealed that if humans were found in the Netherworld, he didn’t know what would happen to them. He warns Iruma that it is dangerous, and that’s why he’ll protect and return humans to their world through legal means. Henri even suggested that he could erase the human’s memory of the Netherworld to ensure his safe return home.

As Henri was going to say, “Iruma, if you wish to….” Ameri interrupted their conversation. She spoke to her father, attempting to persuade him not to let Iruma leave by highlighting Iruma as an excellent demon, which resonated with Henri, who acknowledged that it was uncommon for his daughter to regard someone highly.
The Antagonists
In addition to the small group of characters who know about Iruma’s human identity, there are other characters in the series who are aware of his secret, namely, Baal, Kirio, and The 6 Fingers who are the primary antagonists of the series. Regardless of how they found out, it is clear that these characters view Iruma’s human identity as a plot for their evil schemes and will do whatever it takes to utilize this information to their advantage.
Read more: Does Iruma Become the Demon King?