Name: The Stalker, Nanashi Species: Aberrant Monster Height: 230cm Appearance: A body like a black shadow with unnaturally long limbs and glowing red eyes. Has no mouth or nose. Identity: The most feared stalker roaming the school. It detects sound and presence, relentlessly cornering humans. If Captured: Taken to an isolated basement classroom. Unless the victim escapes using a hidden key, they are transformed into a new anomaly.

Name: The Girl of Reminiscence, Beniko Species: Earthbound Spirit Height: 165cm Appearance: Long black hair, pale skin, and a red sailor uniform. Half her face is hidden by hair, and her eyes are blood-red. Identity: The first of the Seven Wonders, "The Woman in the Red Corridor." She chases anyone who makes eye contact with her in the hallway. If Captured: Locked in an empty classroom. Cannot leave until the riddle written on the blackboard is solved.

Name: The Registrar, Kurose Species: School Anomaly Height: 205cm Appearance: Dressed in a black suit with no eyes or nose. Holds an old attendance book with unnaturally long fingers. Identity: A teacher patrolling the school at night. He attempts to record the names of intruders in his book. If Captured: The victim's name is recorded, and they are treated as a student of the school. Unless the name is erased from the book, they can never return to the original world.

Name: The Phantom Boy, Yu Species: Unknown Non-human Height: 178cm Appearance: Pale silver-blue hair, translucent blue eyes, and fair skin. Wears a black uniform and casts no shadow. Identity: A mysterious boy who moves freely through the school. He sometimes helps the protagonist against anomalies, but his motives are unknown. If Captured: Trapped in darkness and questioned by Yu about the school. Depending on the answer, clues for escape may be gained, but lying results in being warped to a different location.

Name: The Reaper of the End, Shion Species: Reaper Height: 195cm Appearance: Long silver hair, cold silver eyes, and a long black coat. Carries a large scythe, surrounded by a black mist. Identity: The true form of the seventh wonder, "The Monster at the School Gate." The final guardian who manages the school's exit. If Captured: Taken to the top of the clock tower to face a final trial. The school gates will not open unless the trial is overcome.