Marie is a hopeless girl who is harassed by everyone in her class and abused by her homeroom teacher. While despairing over her troubles in the bathroom of the old school building where she regularly meets her teacher for "supplementary lessons", she accidentally starts the rumor of a youkai named Mesomeso who haunts the bathroom. Higanbana gives her the chance to actually become Mesomeso, which she does after being strangled to death by her teacher. Instead of seeking revenge, however, Marie uses her newfound status to help other bullied students in her school.
Secret Test of Character: She and Kanamori were teleported to the bathroom to see who was capable of becoming Mesomeso. She wins due to Kanamori breaking the rules in regards to becoming Mesomeso.
Sixth Ranger: Introducing Mesomeso, the eighth of the seven school youkai.
White Sheep: Just compare her character to the other youkai…
The Worf Effect: While she often tries to help the protagonist, she rarely manages to do anything, much to her dismay. Though she at least talks Yukari out of the suicide option the latter was contemplating.
Higanbana is ranked third among the seven major youkai who haunt the school, also known as the "Dancing Higanbana". She often takes the form of a doll that sits on one of the shelves in the school infirmary, and is rumored to dance around in the middle of the night. She forms an Odd Couple with Marie after she effortlessly starts the rumor of Mesomeso, opening a spot for an eighth youkai.
Anti-Hero: While she helps the desperate Marie from the awful situation her teacher has placed her in, Higanbana's intentions are not exactly good. The antagonists are just worse.
Bad Samaritan: It's part of her nature as a youkai. She may seem to help people, but she really just wants to eat them in the end. The only real exception to this is Marie, especially after she becomes a youkai, though she openly states that she would've eaten Marie if she hadn't.
Break the Haughty: Played for Laughs in "Welcome to the Mirror World". Higanbana gets into a fight with Marie's Mirror Universe counterpart Geragera, who is ranked first among the youkai in the mirror world. By the end of their fight, the once-haughty Higanbana is turned into Geragera's sniveling errand-girl, and even continues to act this way when she meets the real Marie afterward.
Lack of Empathy: She curses and kills humans without a second thought, and she could really care less about her fellow youkai. The only person she even remotely cares for is Marie, if only because she's interested in her capabilities as a youkai.
Youkai are ghost-like creatures who are responsible for mysterious phenomena that occur within the school. Whenever someone gets mysteriously injured or suddenly becomes misfortunate, a youkai is usually the one responsible. The youkai have their own hierarchy based around the school's mysteries, which are caused by the top seven youkai (well, eight counting Mesomeso). Besides these youkai, there are numerous other youkai who try to contend for spots in the hierarchy.
The highest ranked youkai in the school. He is said to emerge from one of the pictures in the school principal's office, and eats anyone he happens across. He also has the ability to erase memories, thus his position as the top ranked youkai.
Beware the Nice Ones: He's said to be a gentle guy most of the time, but he is absolutely terrifying the rest of the time.
Pet the Dog: After Takeshi and Yoko's ghost break the Cycle of Revenge that caused them so much suffering, the Headmaster escorts Yoko's ghost back to Hell and ensures her that she will no longer suffer eternal torment there, allowing her to achieve peace.
Black Tea Gentleman
The Headmaster's right-hand man, also known as the Vice-Principal, unofficially ranked second among the school youkai. He is never seen without a fully-prepared tea set. He makes contracts with humans by offering them his power to escape reality and believe their own lies in exchange for a small portion of their souls. He is currently contracted with Midori Kusunoki.
The second ranked youkai, also known as the "Shinigami of the 13 Stairs". If a human steps on the 13th stair, he forces them into playing a game of tag each day, where if the human ever stops running, they are dumped straight into hell. Granted, if the human can last 49 days of this, they will be free but...
The fourth ranked youkai, also known as "Azami the Vengeful". Using her magical azamis, she can turn bullied kids into bullies themselves.
The fifth ranked youkai, also known as "Kyou of the Mirror".
The sixth ranked youkai, also known as "Renoir of the Art Room". He spends most of his time sleeping within portraits in the art room, but every once in a while awakens to eat. If a human breaks one of the rules regarding Renoir (borrowing a brush from Renoir, giving an incorrect answer as to the artist of one of the portraits in the room, or lying at all during a conversation with Renoir) they are sucked into a portrait where they are doomed to live forever.
The seventh ranked youkai, also known as "Sumire of the Dusk". She is the main antagonist of "Utopia", where she disguises herself as a transfer student named Reiko. Really looks up to Azami, who she refers to as an older sister.
Butt Monkey: Very deliberately. She does it to spawn as many bullies as she can, but her character file mentions she actually takes pleasure in being bullied.
The Chessmaster: She stimulates the desires of Yukari's classmates to bully others so that when the time comes for them to change classes, they may spread bullying throughout the school and allow her to feast on the souls of bullied children. Higanbana thwarts her plan by killing all the bullies in a bus crash.
Expecting Someone Taller: Judging from Michiru's description of him, Marie expected him to be a terrifying and vengeful spirit, and doubted she'd be able to speak on even terms with him, even as one of the eight highest ranking youkai in the school.
Insistent Terminology: The way he's described makes him appear to be a Kitsune but, being the "king of animals", he insists that he is a lion.
Leitmotif: A remix of "Sakutaro no ganbarimonogatari" plays during his appearance.
Little Bit Beastly: While the narrative implies that he may be a fox, he insists that he's really a lion.
The Scapegoat: He's blamed for the "curse" that Michiru tries carrying out in "Shrine of the Guardian Spirit".
Verbal Tic: "Uryuu~!"note Shared with Sakutaro from Umineko
A youkai who haunts the school's music room, also known as "Hameln of the Music Room". According to his legend, anyone who enters the music room at night when no one else is around will hear the sound of his castanets playing, and then will turn into an animal to be lured away to their doom. He is not one of the eight ranked youkai of the school.
Baleful Polymorph: His power allows him to turn students who hear his music to turn into small animals.
Cruel and Unusual Death: Hameln, after cursing Higanbana into the form of a bunny, tries to eat her. Higanbana responds by biting onto his tongue and then eat it along with the rest of Hameln's insides.
Kanamori is Marie's homeroom teacher. He originally defended Marie against her tormentors, but has long since taken to molesting her in the bathroom of the old school building to relieve the daily stress of his job. He is the main antagonist of the first chapter, "Mesomeso-san".
A God Am I: Well, not necessarily a god, but he declares himself to be Mesomeso after strangling Marie to death and pretending to be a youkai to ward off potential witnesses who came because of a Scare Dare.
Beneath the Mask: He'd be a fairly likable guy if he weren't secretly a brutal, animalistic child molester.
Bishōnen: Is said to be very popular with the girls. Well, except for Marie.
Blackmail: Kanamori always videotapes Marie while molesting her, and threatens to expose the tapes in order to keep her quiet. The moment Marie tried to turn this around on Kanamori, it led to her death.
Hoist by His Own Petard: He dies because he broke all the rules regarding the legend of Mesomeso. Mainly, he wasn't supposed to respond to or even look at her, and should've just run away had he not assumed the test was to see who could become a better youkai instead of seeing who could be a better Mesomeso.
"The Reason You Suck" Speech: He lays one on Marie during the poll to see which one of them would become Mesomeso, telling her that she could've solved all her problems ages ago if she'd just grow a backbone and call the police. See Hoist by His Own Petard above for why it would've been better for him to just stay quiet.
Villain Protagonist: The "Mesomeso-san" chapter is as much his chapter as it is Marie's, since it's told from both their perspectives.
Villainous Breakdown: Kanamori has two. The first was when Marie threatened to turn over the evidence of his "supplementary lessons" to the police and put him away, which resulted in him strangling her to death. The other was when he learned he had failed the test to become Mesomeso and that Marie has become the youkai instead — and is ready to take vengeance upon him.
Exactly What It Says on the Tin. She is a friendly and good-natured young woman who works at the school infirmary, and is Higanbana's owner. She is quite knowledgeable on the topic of The Seven Mysteries of the school, and may in fact seem to know more about them than she lets on…
Sensei-chan: A school nurse variation, in the manga at least. Her VN incarnation is a bit more composed.
Takeshi is a photographer and member of the school's journalism club. He was once falsely accused of breaking school equipment by Yoko Numata and her friends; unable to prove his innocence, he became obsessed with finding "the truth" in the pictures he takes. He also harassed Yoko out of revenge by stalking her and sending her photos he took of her in secret, inadvertently causing her suicide. He is the main protagonist of "The Spirit Camera".
Stalker Without A Crush: He used to take pictures of his classmate Yoko from afar and left them everywhere for her to find (even going as far as to clutter her locker with them), all out of revenge for being framed for something he didn't commit. He promptly stopped after she killed herself and her corpse was eaten by the Headmaster.
You Are Worth Hell: When he finds out the kind of suffering Yoko had to endure in Hell, he becomes perfectly content with following her there to be with her if he can't go there in her place.
Yoko is a girl who accidentally broke some school equipment and blamed it on Takeshi to avoid getting in trouble. She committed suicide after Takeshi started stalking her, sending her harassing photos of her and getting her bullied by the whole school, dooming her to an eternity of torment as the youkai's plaything in Hell. Her ghost appears in "The Spirit Camera" as part of Higanbana's bid to eat Takeshi's soul, and again as the protagonist of "One Girl's Day".
Blinding Bangs: While in Hell as a ghost; she loses them once she makes peace with Takeshi.
Pay Evil unto Evil: Subverted. Higanbana brings her back from Hell to kill Takeshi for causing her suicide, but Yoko feels equally guilty when she finds out why he did it, so they forgive each other instead.
Midori is a wealthy student and member of the school drama club who was bullied by other students for flaunting her wealth. Ever since making a contract with the Black Tea Gentleman to get a role in a play she wanted to be in, she has gained popularity and become the most beloved student in her class. In reality, this is all part of an illusion fabricated by the Black Tea Gentleman, who granted her wish to have her literally switch places with another student she was jealous of. She is the main protagonist of "The Princess's Lie".
Freak Out: After Marie frees her from her Dream World, all her experiences of being bullied in the real world hit her like a truck. She only gets a hold of herself once she's returned to the Dream World.
Genre Blindness: When she begins experiencing sharp pains on her body, she initially assumes it's just caused by anxiety over an audition for the lead role in a play. Once these pains become more frequent, and dead bugs appear in her food during lunchtime, Midori reasons that her jealous classmate is using the Black Tea Gentleman's powers to curse her and get the lead role herself. She's actually feeling the pain from the beatings her classmates inflict on her while she's in the Dream World—because of A Glitch in the Matrix, some of their pranks also make their way through.
Laser-Guided Amnesia: While in the Dream World, she has no memory of wanting to switch places with another student and instead believes she made a contract with the Black Tea Gentleman for a role she wanted for a play.
Eyepatch of Power: She's actually said to not need it anymore, but she keeps wearing it anyway.
Freudian Excuse: No one ever believed that she had a sixth sense, making her feel alienated with the world. So when a bunch of girls laughed at her when she insisted that they would be cursed if they didn't apologize for destroying Sakunoshin's shrine, she took matters into her own hands by making up her own curse, one that involved dropping a chair on one of the girls' heads.
Hikaru is a very intelligent cram school student and member of the animal raising committee. He looks down on his more inept classmates, which ended up getting him bullied by them. He vents his frustrations by abusing the rabbits kept on the school grounds, which he is supposed to be caring for. He is the main protagonist of "Hameln's Castanets".
And I Must Scream: His eventual fate (see Karmic Transformation below), which leaves him screaming for Higanbana's mercy until he can no longer scream (as rabbits can't scream out in human language). And even afterward, he is described as attempting to scream for her mercy as she left...
Jerk with a Heart of Jerk: One moment he's petting rabbits after news of them being tortured starts to spread. Then we find out just who's been torturing those rabbits. And if that wasn't enough, we find out that none of his bullies were ever unprovoked in tormenting him; they'd been merely sticking up for a girl Hikaru himself picked on.
Pay Evil unto Evil: He knows it's wrong to torture innocent rabbits. But if Hameln turns bullies into rabbits, then he wouldn't be torturing "innocent rabbits", would he... Of course, you may be surprised how much this trope goes both ways.
Aya is a girl who lost the will to live, but continued to do so because she didn't want anything other than a peaceful, sleep-like death. After hearing the rumors of the 13 steps, she tests it out and accidentally steps on the 13th step, forcing her to participate in Izanami's game. She is the main protagonist of "The Thirteenth Step's Shinigami".
Yuki is a young boy who enjoys art and loves his art teacher, Shintani-sensei.
An art teacher who considers herself the queen of the art room. She particularly enjoys having her favorite young male students model for her, although art isn't all she wants them for...
Michiru's best friend who ends up dying at the beginning of "My Best Friend" after slipping and hitting her head while on vacation with her family. Like Michiru, she loves occult stuff, but compared to her best friend, she leans more towards sci-fi.