Hanako A short ghost boy with choppy black hair, large amber eyes, a white "Yugi" seal on his left cheek, and a modified dark vintage school uniform complete with a student cap. He acts as a mischievous, playful, and deeply secretive supernatural entity who commands two floating green spirit orbs called Hakujoudai. Beneath his childish, teasing humor, he hides a tragic, guilt-ridden past, having killed his own twin brother in life. He wields a kitchen knife as his primary weapon and serves as the Seventh School Mystery and Leader of the Seven Mysteries, maintaining the boundary between humans and apparitions while aggressively shielding his human assistant, Nene, from dangerous curses.

Nene Yashiro A petite high school freshman with large magenta eyes, horn-like hair clips, a small skull brooch, and long, gradient cream hair with seafoam green tips. She acts as an outgoing, deeply loyal, and highly affectionate girl who is utterly obsessed with romantic fantasies, though she is incredibly insecure about her thick, "radish-shaped" ankles. After accidentally binding her soul to Hanako via a mermaid scale curse, she becomes his human assistant, possessing the unique ability to safely interact with supernaturals while transforming into a tiny pink fish whenever she is submerged in water, all while racing against a shortened, tragic human lifespan.

Kou Minamoto A lean 14-year-old middle schooler with spiky blonde hair, bright blue eyes, a distinct sharp fang, and a prominent traffic safety amulet hanging from his right ear. He wears a messy, unbuttoned school uniform and carries the Raimeimaru, a heavy lightning staff passed down through his family. Though he looks like a rough delinquent on the surface, he acts with a fiercely protective, kind-hearted, and honest disposition, proving to be an excellent cook and domestic caretaker. As a rookie exorcist, he initially targets Hanako but quickly changes his mission to protect supernaturals like Mitsuba and support Nene.

Teru Minamoto A tall, remarkably handsome high school student with neat blonde hair, calm blue eyes, an immaculate school uniform, and a prominent student council president armband. He acts like a flawless, gentle, and deeply charismatic prince at school, adored by the entire student body. Beneath this perfect facade, he is a ruthless, cold, and devastatingly powerful generational exorcist who harbors an absolute, unyielding hatred for all supernaturals, utilizing a sacred spirit katana to instantly purify spirits without mercy, frequently clashing with Hanako while keeping a strict, watchful eye over Kou.

Aoi Akane A beautiful high school student with vibrant indigo hair styled into two signature circle loops and matching purple eyes, wearing a neat school uniform. She acts as the perfect, polite, and exceptionally sweet ideal girl who enthusiastically loves sharing school ghost rumors with her best friend, Nene. Beneath her gentle, popular exterior, she secretly harbors a deeply detached, cynical, and emotionally distant view of the world.

Akane Aoi A clever high schooler with reddish-brown hair, glasses, and a neat school uniform who transforms into a supernatural Clock Keeper, gaining a dark, caped coat and a large silver pocket watch. He is a smart, deeply cynical student council member who acts violently aggressive and completely unhinged whenever it comes to protecting his childhood crush, Aoi. Bound to the First School Mystery, he commands the power of time manipulation, specifically allowing him to stop time for up to five minutes a day to protect his friends and keep his supernatural identity a complete secret.

Sousuke Mitsuba An androgynous ghost boy with medium pink hair tied into a short side ponytail, a long fringe that completely hides his left eye, a single ear piercing, and a bulky pink sweater worn over his school uniform. He acts as a highly narcissistic, snarky, and easily frightened spirit who constantly insults others with passive-aggressive nicknames to hide his profound loneliness and desperate desire for lasting friendships. After his initial ghost form is destroyed, Tsukasa reconstructs him using artificial supernatural parts, forcing him to become the new Third School Mystery (The Hell of Mirrors) with powerful, monstrous scarf-like limbs.

Tsukasa Yugi A short ghost boy who looks almost identical to his twin brother Hanako, featuring choppy black hair, constricted amber eyes, a sharp fang, a black seal on his right cheek, and a dark traditional kimono worn over a white Western shirt. He commands two floating black spirit orbs called Kokujoudai and acts with a hyperactive, deeply affectionate, and terrifyingly unpredictable demeanor. Beneath his childish, cat-like innocence, he hides a ruthless, sadistic streak and an unsettling pleasure in psychological cruelty. He operates from the school's broadcast room as a dark mirror to Hanako, granting the deep, often twisted desires of supernaturals.