The protagonist. She has a crush on her childhood friend, but ironically, she has a crippling fear of sex and sexuality.
- A-Cup Angst: While by no means flat, Kazusa finds herself coming off as inadequate in comparison to Niina's bust size.
- Aren't You Going to Ravish Me?: After coupling with Izumi, she tries to seduce him by wearing racier underwear and flirting. His reluctance to do so makes her frustrated and insecure, when the reality is that he wants to cherish her and can't deal with the idea of his longtime friend and crush also being someone he can have sexual thoughts about.
- Betty and Veronica: Plays Izumi's Betty opposite of Sugawara's Veronica for Izumi.
- Childhood Friend Romance: A rather late blooming one, but she develops romantic feelings for her neighbor and childhood friend Izumi during high school.
- Love Epiphany: Realizes that she was in love with Izumi rather early in the series, in chapter 2.
- Paralyzing Fear of Sexuality: She has it bad. To the point that one of the first things she does upon interrupting Izumi's private moment is to get out of dodge.
- Official Couple: With Izumi lest Niina disrupts it.
- Properly Paranoid: Turns out, Kazusa was right to fear Sugawara going after Izumi, since that's exactly what happens after she and Izumi start dating.
- Stock Shoujo Bullying Tactics: Because she was close to Izumi, one of the more popular boys in school, she was the subject of ire for quite a few schoolmates and they wasted no time reminding her of that.
Kazusa's best friend often referred to as a "crane" for her fragile appearance. Gradually began to develop feelings for Izumi, thus getting swept into a love triangle between her and Izumi.
- Armor-Piercing Question: Sometimes unintentionally, sometimes very pointedly, she has a habit of poking at the hidden desires in others and forcing them to confront their feelings.
- Betty and Veronica: Plays the Veronica to Kazusa's Betty for Izumi.
- Bifauxnen: Can pass off as a handsome boy.
- Cloudcuckoolander: She's deeply weird, to the extent that even her friends find themselves confused and unsettled by her half the time.
- Dark and Troubled Past: Was harassed some years ago, hence her attempts to ignore boys. Later episodes also reveal that she was groomed by her acting teacher until she eventually believed that she was in love with him. Even a few years later and Niina still goes to him for advice.
- The Dog Bites Back: Punches her acting teacher in the face when he tried to have sex with her.
- Even the Girls Want Her: Momoko doesn't really count as she's strongly suggested to be a lesbian, but even Kazusa admits that she's a little attracted to Niina (and therefore, can't really blame Izumi for the same).
- Evil Cannot Comprehend Good: Not necessarily evil per say, but Niina was so used to having young men shout out to her, she is genuinely taken aback when Izumi refuses her advances, and tries to push the fact that he was still "hard" from it.
- Hidden Buxom: Episode 6 reveals her having a pretty sizable chest, much to Kazusa's chagrin.
- Hypocrite: Dislikes having attention drawn to her because of her appearance, and yet, one of the primary ways that she tries to rope Izumi in is to fake someone groping her and then taking Izumi's hand and placing it on her butt.
- Ill Girl: Frequently states that she's dying, and looks and acts the cliché. It's probably not true, and she admits when confronted that she's speaking in terms of the human lifespan in comparison to the universe.
- Lust Object: In the last few chapters, Izumi admits that he's primarily sexually attracted to Sugawara, but still romantically attached to Kazusa at the same time.
- Manipulative Bitch: Fortunately she uses it almost entirely for good, but she's very savvy about the behavior of others. Megumi's attempt to bully her is shut down very quickly, simply by playing Megumi's Bitch in Sheep's Clothing persona against her. Less positive later on, when she's determined to make Izumi fall for her and deliberately flaunts the relationship in Kazusa's face.
- Mentor Archetype: Subverted, and lampshaded. For most of the series Niina seems very Wise Beyond Her Years about relationships, and with her savviness about emotions, mature appearance and stoic demeanor takes the role of Stealth Mentor to the other girls. Momoko confessing her feelings even causes Niina to note that this is the time when she would normally give sagely advice, but that she actually has no idea what to say. Most of her more mature and sagely moments are near identical copies of those her former teacher and abuser used on her, suggesting she's shallowly trying to emulate him. And in the final episode she outright admits she was bullshitting, and she's as much of an emotional mess as any one of them.
- Psychotic Smirk: Briefly sports one when she taunts Izumi about making him "hard."
- Shrinking Violet
- The Sociopath: Ticks most of the boxes. She is skillful at manipulation or reading people like books; she has little hesitation at trying to get Izumi despite knowing that it would hurt Kazusa; her desires to have sex serve as a form of stimulation for herself; and while she isn't overly prideful about her looks, she nevertheless is aware of others' perceptions of her thus causing her to feel genuinely exasperated when Izumi refuses her attempts at the train station. Most of this however can be explained away as a result of her being molded by her acting teacher.
- Troubling Unchildlike Behavior: Niina has taken to warding off unwanted attention from boys and men by pretending she's a sex worker with an STD she's happy to pass on. And her acting teacher has taught her to do this since before she entered middle school.
The club president who resents her interest in the opposite sex primarily due to her upbringing.
- Character Development: Through her becoming infatuated with Shun, Rika had gradually outgrown the ties with her upbringing and changes her mind on boys.
- The Glasses Gotta Go: A rather classic take on the trope. After Shun tells her she looks good without her glasses, she finally decides to stop wearing them, change her hairdo, and switch to contacts. The class and Shun approve of the new look.
- Huge Schoolgirl: She's extremely tall, which unfortunately combines with her prickly personality to make her somewhat intimidating.
- Hypocritical Humor: Derides her female classmates for being harlots, but she has interests towards boys that she tries to suppress.
- Large Ham: Prone to doing dramatics regarding the circumstance.
- Meganekko: Starts out as this until she considers using contacts when Shun said she looked cuter without them.
- Official Couple: With Shun.
- Slut-Shaming: She's extremely guilty of it, which pretty much turns the whole class against her.
- Sour Prudes
- Thought-Aversion Failure: Frequently berates the club for thinking about or discussing sex... which inevitably leads to her thinking about and discussing sex.
- Tsundere: Towards Shun to the point that she forces him to write a 50-page report on what he liked about her.
One of Kazusa's friends. She slowly begins to develop a one-sided crush on Sugawara after quickly befriending her.
- All Love Is Unrequited: She gets depressed when realizing that Sugawara most likely liked Izumi instead of her.
- Does Not Like Men: Pretty much asks why girls are supposed to go after men when comparing their physiques to those of girls. Best exemplified where she gets gradually disturbed by Satoshi's advances until she eventually blew up on him.
- Incompatible Orientation: She learns the hard way from Kazusa and Sugawara that some girls just don't see other girls as romantic interests.
- Nice Girl: She's notes herself that among all of the literature club, her and Sugawara are the only normal, easy to get along with ones.
- Lipstick Lesbian: Very feminine, and hinted throughout the story to be more into girls than boys. She turns out to have a crush on Sugawara, who doesn't feel the same.
A short girl who writes novels and erotica. When one of her publishers derided her novel, she decides to "get experience" through an online adult chatroom, and even stages an encounter which ends with her realizing she was seeing one of the school faculty members.
- Death Glare: Gave several teachers this unintentionally when she and the other girls were trying to find an advisor for the literature club to prevent it from being disbanded.
- Hot for Teacher: Develops an aggressive crush on Yamagishi, but it ultimately ends up as Unrequited Love; he's not attracted to Hongo at all as a woman (being a high school girl), instead preferring a fellow teacher.
- Manipulative Bitch: She blackmails her teacher into being the new advisor for the literature club.
- Stylistic Suck: It's not awful, but from what we see of her writing her publishers are right to cast doubt on her ability to write convincing erotica.
- Vitriolic Best Buds: Her relationship with Yamagishi is rooted in blackmail, sexual abuse(by her) and she frequently pours insults onto him, but ultimately they both seek out each other's company and are frequently shown chatting quite amicably about their shared interests.
Kazusa's childhood friend.
- A Date with Rosie Palms: Is caught doing this by Kazusa.
- Chick Magnet: Since middle school, which has led to a great deal of trouble for Kazusa.
- He Is All Grown Up: The main complication in his relationship with Kazusa—not only because she feels weird about being sexually attracted to someone she once thought of as a "short, clumsy, absent-minded little brother, but because many other girls took an interest in him as well and started treating Kazusa as an obstacle to be removed.
- Innocently Insensitive: Tries to explain his addiction to trains to Kazusa only to then make it abundantly clear that he didn't feel that way for anyone else, not even for her.
- Official Couple: With Kazusa lest Niina had something to say about it.
- Oh, Crap!: Has this reaction when Kazusa catches him in his private moment.
- Rail Enthusiast: He reads Train Tables for entertainment; he has posters of trains in his room. He even listens to a song called "Train Train" while masturbating to a movie about a woman getting molested on a public train.
A snobbish high school girl that often antagonizes Kazusa.
- Alpha Bitch: Is apart of the popular clique of girls.
- Bitch in Sheep's Clothing: She acts entirely sweet and innocently in front of Izumi, in stark comparison to how she is around everyone else.
- Break the Haughty: Doesn't take Izumi rejecting her all that well which potentially implicates that she was lying about her previous sexual encounters.
- The Bully: Often bullies Kazusa by poking fun at her looks or inability of getting laid.
- Hate Sink: An abrasive, conceited girl who tries to make Kazusa feel inadequate compared to her.
One of the more popular girls in the school. Primarily because of her looseness. She later befriends Sonezaki, giving her advice on dating.
- Gyaru Girl: Tanned, blonde, and unashamedly sexually active.
- Nice Girl: Treats Rika respectably and gave her advice on dating.
- Slut-Shaming: Twice.
- Done early one by Rika when she badmouths Junjou and her friends explicit conversation. Rika later apologizes after she gets to know Junjoe better.
- Done by Junjou and Rika's homeroom teacher(!) in announcing to the class her (arguably private) reason for dropping out of school.
- Small Role, Big Impact: She inadvertently encouraged Rika into confessing to Shun.
- Teen Pregnancy: Drops out of school due to this.
A boy that Momoko "dated" prior to her realization of her sexuality.
- Hate Sink: He was a narcissistic boy who decides to date Momoko Sudo, ignorant of him making her feel uncomfortable. When she explodes at him at the culture festival at the school, he tries to force her to apologize for embarrassing him in front of his friends and calls her a crazy slut upon realizing that she was never in love with him.
- He-Man Woman Hater: Has some shades of this. He always comments on how women were more weak than men in some areas. He later asks Momoko if she was a slut when she dated him without being romantically interested in him.
- It's All About Me: Never cared for Momoko and was insulted when she embarrassed him in front of his friends.
- Jerkass: While he initially was overbearing, at most he seemed ignorant of Momoko's feelings. However, his true nature is exposed when he tries to force Momoko to apologize to him for her behavior at the culture festival under the threat of her leaving the cram school.
- Karma Houdini: After making Momoko feel worse about herself, Satoshi gets off unscathed and even found himself another girlfriend.
- Kick the Dog: Calls Momoko a crazy slut at Momoko's visceral reaction towards grabbing her hand.
One of the teachers of the school. He is blackmailed into becoming the advisor of the literature club after Hitoha discovers his account on an online adult chatroom.
- Above the Influence: Denies any attraction to underaged girls and to his credit repeatedly rejects Hitoha's sexual advances.
- Butt-Monkey: Gets the short end of the stick continuously from getting blackmailed into becoming the club adviser to getting kidnapped and held hostage by the main girls as part of their protesting of the school's ban on romantic relationships.
- Extreme Doormat: Despite being an adult and a teacher, his students push him around with ease.
- Hidden Depths: It shouldn't be that surprising since he is a teacher, but when attending the literature club meeting he proves to be quite insightful about the material.
- Oh, Crap!: Realizes that the girl he was talking to online was Hitoha and subsequently tries to run.
- Screw This, I'm Outta Here!: Bails upon seeing that Hitoha was the girl he was talking to online.
- Smug Snake: Not a bad guy, but he's smug, arrogant, and has asperations of being a Deadpan Snarker. It would be more convincing if his every encounter with Hitota didn't leave him utterly humiliated in some way.
- Vitriolic Best Buds: Hitoha blackmails, sexually assaults and insults him constantly, and he is often smugly disdainful of her talent and personality. Despite this they both seek out each other's company and are frequently shown chatting quite amicably about their shared interests.
A fellow teacher of the school that Yamagishi fancies.
- Amazingly Embarrassing Parents: They have a night with Kazusa where they all slept together in a cot when they were fondly thinking back on the day she was born.
Niina's former acting teacher whom she fell in love with when she was younger. He was also implicitly (and outright confirmed by Niina herself) to have been a pedophile.
- Big Bad: Sets the conflict of the story into motion.
- The Corrupter: Stages Niina's fighting with Kazusa over Izumi's affections.
- Dirty Old Man: Caressed Niina's leg when she was a young girl. While it was per Niina's request, he nevertheless kissed a high school girl on the lips. Though apparently despite Niina knowing of his true nature, she makes it clear that he never resorted to doing anything physical with her even when she flung herself on him. However, episode 11 throws that into considerable questioning as when Niina allows him to consummate their relationship, she realizes that all of his previous actions on her were acts of molestation, implicating that she hadn't realized she was being assaulted until that moment.
- Hate Sink: He was Niina Sugawara's acting teacher who was responsible for warping her mind. A pedophile, he molested Niina when she first enrolled at his school and psychologically manipulated her for years into believing she was in love with him. When she left, Hisashi continues to conduct mind games on his young female students taking perverse satisfaction in warping their minds to get off on their innocence.
- Karma Houdini: Despite getting rightfully punched out by Niina, that nevertheless leaves him free to psychologically break and groom more potential students.
- Laser-Guided Karma: Gets punched in the face by Niina when he tried to consummate their relationship.
- Muse Abuse: Literally in the case of Niina, but he also encourages her to set up the whole conflict of the show due in part to it's relevance to his artistic sensibilities. He reacts to her betraying her best friend in the same way one would to a stirring theater production.
- The Sociopath: Plays his former student Niina as a fiddle only valuing her for that piece of innocence she had left.