His name when he was human was Yugi Amane. The 7th of Kamome Academy's Seven Mysteries, Hanako-san of the Toilet. Though he looks like a cute and mischievous boy, he is actually a powerful supernatural. He usually speaks in a sly and lighthearted manner, but he carries a dark past and deep guilt inside. He plays the role of maintaining the balance between humans and supernaturals. While he teases Nene, he is often shown to truly cherish and try to protect her. A complex character who hides loneliness and sadness behind a bright expression.

An ordinary high school girl who summoned Hanako-kun. She has a pure and honest personality and dreams of romance. Initially clumsy and easily frightened, she gradually becomes braver and grows as a person. Due to a mermaid's curse, she is afflicted by a water-related curse. Because of this, she sometimes turns into a fish. She has a warm heart, trying to understand Hanako and even accepting his past. As the story progresses, she is one of the characters who shows the greatest emotional growth. Recently, issues regarding her lifespan have emerged.

The son of a family of exorcists who defeat supernaturals. He has a strong sense of justice and an honest, passionate personality. Initially, he views Hanako as an enemy, but he gradually begins to feel complex emotions toward him. He values his friends and wants to correct what is wrong. He is a character who contemplates the relationship between supernaturals and humans, rather than being a simple 'exorcist'.

Kou's older brother. He has the image of a perfect student council president within the school. He is highly capable and possesses great charisma. While gentle on the outside, he is extremely cold and decisive toward supernaturals. He cares for his younger brother but is somewhat clumsy at expressing it. As a person with a human-centric worldview, he often stands in opposition to Hanako.

A boy who became a supernatural after dying. He was a lonely child who desperately wanted friends. His relationship with Kou is portrayed as particularly significant. He appears cute and bright, but he has a strong desire to be recognized. A character who represents the themes of 'meaning of existence' and 'memory' in the story. The 3rd of the Seven Mysteries, the supernatural who is the master of the Hell of Mirrors.

Nene's best friend. She has a realistic and perceptive personality. A reliable friend who sincerely worries about Nene. As the story moves into the latter half, she occupies an important position rather than being a simple supporting character. Recently, she was kidnapped by a supernatural.

He has a strong desire to protect Aoi, whom he loves. When active as a supernatural, he is sly on the outside but serious on the inside. Normally, it is the opposite. He comes to play an important role on the boundary between humans and supernaturals. The current representative of the 1st of the Seven Mysteries, the Clock Keepers.

A supernatural who grants wishes to other supernaturals.

The 5th of the Seven Mysteries, the supernatural who is the master of the 4 PM Bookstacks.

She has a contract with Tsukasa and is beautiful. A third-year student in the high school division of Kamome Academy. The object of Natsuhiko's one-sided affection and pursuit. She is also a senior who treats Mitsuba kindly. While her personal goals remain unknown, she plays the role of spreading manipulated rumors about supernaturals.