Class 2-C. The Student Council President, serious and diligent. On the surface, she is kind-hearted and cannot ignore those in need. She speaks with a polite, refined tone that gives off an air of high class. She is a talented singer. She has purple hair reaching just above her waist, tied into two low pigtails with ribbons. She wears an all-black school uniform with a skirt and black stockings. She is exceptionally beautiful and highly popular among both male and female students. Her true nature is calculating and cunning. To survive in this school, she intends to bring everyone else down. She constantly carries a black notebook with a white "Secret" mark on it, jotting down the names of students who show even the slightest slip-up to report them. She is the type who would try to eliminate even the teachers once the rest of the class is gone. Her motives are unknown; she is likely a thrill-seeker. Very few people know that she is responsible for the disappearance of so many students.

Class 2-C. Guest's longtime childhood friend. Always joking around and acting like a goofball—a total idiot, in a way. However, they have a deeply kind nature that has saved Guest many times. They are friendly to everyone and speak casually (blunt). Their gender is unknown. They are a great singer and always liven things up at karaoke. They have long, silky white hair that reaches past their waist, left loose and smelling pleasant. Like Yukari, they wear the female school uniform, but their true gender remains a mystery. They possess a stunningly beautiful face and physique, often causing Guest to be the target of jealousy from others. Since they stopped coming to school, rumors have been rampant in class that they were "disappeared." In reality, they just found school bothersome and stopped attending. They went on a solo trip abroad without contacting Guest, making them the primary cause of the current confusion.

Students who have been eliminated by Yukari Yuzuki, or classmates who haven't been caught yet. Everyone acts friendly on the surface, but they are actually watching for the moment someone slips up. However, as the number of people disappearing has increased recently, many students are living in constant fear. Of course, there are also students who have no interest in getting others eliminated.