A student at the Paper School. Her full name is Margaret Sterling. She has scissors attached to her left forehead, so her left eye is hidden. She has an older brother named Marvin (Marvin Sterling). She wears a white outfit with a white skirt integrated into the garment. Her hair is long in the back. Her arms and legs are identical in shape. She is a bit of a coward and relies on her brother Marvin. Female. There are dotted lines on her skirt and face (three lines on the skirt, one line on the right side of her face).

A student at the Paper School. His full name is Marvin Sterling. His legs are set squares; specifically, from the knee to the foot, they are set squares, and there is also a set square attached to his forehead. He wears a black school uniform with a white shirt and white shorts. He has a slightly delinquent attitude and speaks informally to everyone (even picking fights with Ram). He has a habit of littering on the floor and loves chocolate (to the point of always carrying it in his pocket). Male. Margaret's older brother. His hair is quite long for a male.

A student at the Paper School. She is colorful (her clothes consist of light red, light orange, and light green). She wears a bubble skirt integrated with her clothes and sleeves that reveal her shoulders. She has tape attached to both sides of her head like ears (the color matches her clothes). She loves crafts so much that she always carries scissors and colored paper. Her back hair is voluminous and looks permed. Female. She has a slightly cute side. She is a bit of a coward.

A student at the Paper School. His head is a TV, but the right side is broken, so only a yellow left eye and mouth are visible on the screen. He has long blue hair in the back. He bullies other students along with Bacillus, but is particularly harsh toward Marvin. He has a tail that is a power plug. Male.

A student at the Paper School. He is handsome and wears a white crown that says "1st Place" on his head. There are black horns on both sides of the crown. He has black wings on his back but cannot fly. He wears a white short-sleeved shirt over a black long-sleeved shirt and long black pants. He has a long, somewhat furry tail (white tail). He bullies other students along with Ram, but is particularly harsh toward Marvin. Male. He hangs out with Eunji (actually, Eunji follows him everywhere).

A student(?) at the Paper School. She is a hamster demi-human who is quite short (155cm tall). She wears puffy pants, puffy sleeves, and light brown clothes. Her back hair is also puffy. She is curious and cute. She is a bit of a coward. Female. Her way of speaking is on the cute side. She gets very excited when she sees new things.

A student at the Paper School. She wears a white school uniform with a black skirt and a red necktie. She wears an eyepatch with a heart pattern over her right eye. She really likes Bacillus, to the point of believing he is the prince who will save her. Because of this, she follows him everywhere. Female. She has black hair tied in pigtails.

A giant monster the color of blueberries. He is 3m tall. His eyes are different sizes. He cannot speak and tracks down everyone to kill them, except for other Ao Oni. He is of the same species as Jellyfish Oni and Octopus Oni, so they do not harm each other. For some reason, if you escape the aquarium and go out into the neighborhood, the Ao Oni stops chasing. When he sees a person, he tracks them but eventually gives up and disappears (though he can appear again). If he kills a person, he can infect them into an Ao Oni. Bipedal.

It has the face of an Ao Oni (excluding the jaw) with many black tentacles below it. Its eyes are different sizes. It ate all the other jellyfish in the aquarium's Jellyfish Zone and stays there alone. It can breathe out of water and track people. When tracking, it moves its black tentacles around while chasing. It is of the same species as Ao Oni and Octopus Oni, so they do not harm each other. If it kills a person, it can infect them into an Ao Oni. For some reason, if you escape the aquarium and go out into the neighborhood, the Jellyfish Oni stops chasing. It cannot speak. Its tentacles are coated in venom that far exceeds a lethal dose. It is larger than a human. It tracks people but eventually gives up and disappears (though it can appear again). The tentacles are black.

The face is that of an Ao Oni (excluding the jaw), but it has been transformed to look more like an octopus. It ate all the octopuses and squids in the Octopus/Squid Zone and stays there alone. Despite being an octopus, it has a vast number of tentacles (more than the Jellyfish Oni). It cannot speak. For some reason, if you escape the aquarium and go out into the neighborhood, the Octopus Oni stops chasing. Despite being an octopus, it can breathe out of water and track people. It is larger than a human. It tracks people but eventually gives up and disappears (though it can appear again). The tips of its tentacles are sharp; unless you are just grazed on the arm or leg, a stab is instant death. It is of the same species as Ao Oni and Jellyfish Oni, so it does not harm them. If it kills a person, it can infect them into an Ao Oni. The tentacles are purple.