Dressed in a black suit, his body is inorganic and pitch-black like a shadow. There is a luminous part where his right eye should be, from which cracks run across his entire face. He wears black gloves, but similar cracks exist on the skin-like area between the gloves and sleeves. A mist-like substance emanates from the cracks on his head.

Appears as a two-headed mannequin dressed in a tuxedo, making creaking sounds when he moves. As his appearance suggests, his motif seems to be the wooden mannequins used for sketching art. However, he himself does not seem to be fond of his own appearance. He uses difficult, archaic language and speaks in a theatrical tone, characteristic of a self-proclaimed artist.

A tall woman with long black hair, red skin, and a white dress. Her head is a ball of fur covered in winged eyes, and her mouth is filled with jagged, irregular teeth, radiating an ominous atmosphere. Due to her noble attire, she is called "Madame" by members of Gematria and students of the Arius Branch School. An arrogant individual who views children as things for adults to exploit, she does not hesitate to eliminate those who have outlived their usefulness or stand in her way.

A headless man in a coat holding a cane is "Decalcomanie," and the man in the silk hat facing away in the photograph held by Decalcomanie is "Golconda." As he himself states, he is non-existent and does not appear outside of the photograph. According to Golconda, the two are partners symbolizing "virtual image" and "non-existence," and are merely "symbols."

Appears as a painting with an eerie face depicted on it, held by Decalcomanie. He was formerly known as the "Anonymous Traveler." Unlike the polite Golconda, he speaks in an intimidating tone and claims that this world was created for the sake of the "Protagonist," the "Sensei."

A new form following Golconda and Francis, appearing from the Main Story Volume 2 Prologue. He is characterized by an old-fashioned television set attached to Decalcomanie's head. He appeared before Sensei around the same time the new General Student Council President emerged.

A former member of Gematria who was expelled and confined in a prison-like place. He has a creepy, mask-like monstrous face characterized by a black surface, multiple eyes with clock faces for pupils, and the Roman numeral "XVIII" (18) engraved on his forehead. He refers to himself with the humble first-person pronoun "Shousei."

A headless man in a coat holding a cane is "Decalcomanie," and the man in the silk hat facing away in the photograph held by Decalcomanie is "Golconda." As he himself states, he is non-existent and does not appear outside of the photograph. According to Golconda, the two are partners symbolizing "virtual image" and "non-existence," and are merely "symbols."