Nozomi Torii. Nickname: Zom. A 6th-grade student in Class 1 at Reida Elementary. A bright, proactive boy with excellent athletic nerves. He dives into dangerous places without hesitation to save his friends, acting aggressively while assessing the situation. He is characterized by wearing a green camouflage hoodie pulled low and carrying a green backpack. He has a cat-and-dog relationship with Mr. Raduo Saruyama and is openly rebellious toward teachers. While getting caught up in the Seven Wonders and school anomalies, he aims to escape by cooperating with his friends. Though usually high-spirited, he cares deeply for his comrades and will never leave them behind. He has the courage to step forward even in terrifying situations and values their bonds. Combining proactiveness with a caring nature, he is a reliable presence in times of peril.

Dai Utsushima. Nickname: Utu-sensei. A 6th-grade student in Class 1 at Reida Elementary. A boy who is a bit of a coward and prone to mistakes when nervous or panicked, yet tries to overcome danger with his friends. He is characterized by navy blue clothes, brown shorts, square glasses, and a blue backpack. Caught in the school's anomalies, he aims to escape alongside Zom and Koneshima. Despite his fear, he never abandons his friends and thinks for himself when danger nears. While he panics in tense moments, he also has a side that lightens the mood during conversations. He possesses a compassionate side that refuses to leave others behind even when terrified, and his growth through the incident is very striking.

Takayuki Koneshima. Nickname: Koneshima. A 6th-grade student in Class 1 at Reida Elementary. A bright, energetic, and high-spirited boy who values group action. He is characterized by a white shirt, red suspenders, red shorts, and a red backpack. Caught in the mysterious school incidents, he aims to escape with Zom and Utu-sensei. He is highly proactive and often faces danger head-on with his friends. While he leads others with his cheerful personality, he harbors a significant secret regarding his family behind the scenes. This secret is deeply tied to the story's events, and his family life is complicated(?). He is a vital figure who possesses not just brightness and energy, but a strong desire to protect his friends.

Tonpei Momose. Nickname: Ton-ton. A serious boy serving as the disciplinary committee member in Class 1, Grade 6 at Reida Elementary. He values discipline and holds a relatively responsible position among his peers. He is characterized by a dark purple school uniform, a disciplinary committee armband, and a pink backpack. Caught in the events involving the school's Seven Wonders, he moves through the anomalies with his friends. He goes missing, and the events surrounding him become the catalyst for the others to take action. Because of his serious nature, he cares for those around him even in danger and values cooperation. Even after disappearing, he remains an important presence to his friends, and the mysteries surrounding him significantly impact the story. He possesses a stone statue (Roboro).

Robota Amano. Nickname: Roboro. A 6th-grade student in Class 1 at Reida Elementary. Despite his small stature, he has a loud voice and a strong presence. He is characterized by a yellow T-shirt with the character for 'Heaven' (天), blue shorts, round glasses, and a yellow backpack. Caught in the school's anomalies, he is depicted as a crucial figure in the story. He is Eto's younger brother, and his disappearance is a major trigger for the incident. While deeply connected to his friends, he is also tied to the Seven Wonders and the school's hidden history. His relationship with his brother Eto is vital, as he is the focus of Eto's search. He is a key person harboring secrets linked to the incident. He has been turned into a stone monkey statue.

Eto Amano. A detective currently investigating Reida Elementary to find his missing younger brother, Robota. He is characterized by an orange trench coat, a yellow scarf, and red gloves. Driven by a strong love for his brother and a sense of responsibility, he enters the dangerous school to continue the search. Upon learning that children are involved, he pursues the truth behind the anomalies while protecting them. While he tries to judge situations calmly as an adult, he shows intense emotion regarding his brother. The brotherhood with Robota is a central element of the story, and his actions lead to the heart of the case. He acts as a reliable figure for the children. His motivation stems from his feelings as an older brother; he joins the group in the music room. Weapon: Gun. For some reason, he is playing the piano in the music room. A theory has emerged that he was childhood friends with Saruyama.

Raduo Saruyama. A physical education teacher and the homeroom teacher for Class 1, Grade 6 at Reida Elementary. He is characterized by a blue hat, a blue tracksuit, and a whistle around his neck. While he urges students to go home, he is a mysterious teacher who attacks students with a grass-cutting sickle during the anomalies. He has a particularly bad relationship with Nozomi Torii, frequently clashing with the rebellious Zom. However, as the story progresses, the circumstances he carries become clear. Despite being a teacher, his actions are full of mystery, and he has a massive presence as a key figure. His past and his relationship with the students are keys to the story, placing him in a complex position that isn't just a simple villain. A theory has emerged that he was childhood friends with Eto.