Initially, the seeming protagonist of the series (as much as a slice-of-life series can have a protagonist). A shy freshman when introduced, he gradually grows to accept his interests in the club.
- Ascended Fanboy: Eventually becomes a manga editor.
- Audience Surrogate: At the beginning of the first series, his introductions to the other Genshiken members are also the readers' introductions. He grows out of this role due to his Character Development.
- Covert Pervert: At the beginning. It fades off as he opens up to his otaku side more and more.
- The episode where he acquires a computer to play eroges is a turning point for this.
- Demoted to Satellite Love Interest: Sasahara's character arc focuses exclusively on his relationship with Oguie after they finally get together. After the series was Un-Canceled as Genshiken Nidaime, Sasahara went from the main character to Demoted to Extra as the focus shifted squarely to Oguie as the new main protagonist. This makes perfect sense, as Sasahara graduates, has little reason to interact with the other characters, and moves Out of Focus, and Oguie takes his place as president of the titular club.
- Extreme Doormat: He lampshades this.
- Lovable Coward: He'll often back down from challenges (like picking up a vendor form right after the first ComiFes ended), but he's an entirely sympathetic character.
- Nice Guy: Too much sometimes.
- Out of Focus: In Nidaime, even though he is the current president's boyfriend.
- Shrinking Violet: He's a bizarre male equivalent at the beginning of the series.
- Will They or Won't They?: With Ogiue. They did.
The first member of the Genshiken whom Sasahara meets, Kosaka is an oblivious guy who remains smiling practically all the time. Because of his good looks and outgoing demeanor, people often don't believe he is a diehard otaku, particularly of video games and, much to Saki's chagrin, eroges.
- The Ace: A more down to earth example than most, he is athletic, good looking, and taught himself how to program in a month.
- Aww, Look! They Really Do Love Each Other: For a long time it's ambiguous on if he actually returns Kasukabe's feelings, but this gets clarified when he actively comforts her during her Heroic BSoD.
- Bishōnen: The reason why nobody suspects him of being an otaku.
- Brutal Honesty: He has no qualms about speaking about any elephant in the room. He's fully aware of this; he even declines to help get Sasahara and Ogiue together because he knows he tends to be too blunt.
- Captain Oblivious: Part of the above is that he has absolutely no read of when he should say the truth or how he should say it. There's also the note under Oblivious to Love, which is just part and parcel of his obliviousness in general.
- Cloudcuckoolander: It's not entirely clear whether he even realizes social cues and mores even exist. He's just such a cheerful and happy-go-lucky guy that he doesn't care, and all that combines to him being weird to everyone.
- Completely Missing the Point: All the time (except when gaming).
- Genius Ditz: While he appears to be extremely manipulable and oblivious to most things, he is unbeatable at video games and manages to secure a respectable career at the end of the first series (after taking only a month to learn how to code, something people usually go to college for two-four years to learn).
- Oblivious to Love: Saki may as well have been flirting with the wall for all that Kosaka noticed her at first. He only realized that she liked him when Madarame just came right out and said it.
- Nice Guy: Just about the only way he'd ever say anything even remotely mean to someone would be if he just didn't know it was mean. That said, he's not very good at telling what might be mean.
- Perpetual Smiler: The closest he ever came to not smiling was when, early on, he wistfully noted that he didn't think Saki liked him, even though an omake revealed that she was interested right from their first collegiate meeting.
- The Pollyanna: Commented on by Sasahara, who finds it useful to have someone who remains cheerful even in a crisis.
- That One Player: Saki even invoked this, using Kosaka's skill at video games to intimidate prospective members out of joining back when she was intent on getting Genshiken to disband.
- Wholesome Crossdresser: He crossplays for a sale at the con and one of the before-story images has him in a maid outfit.
- In Nidaime he gets back in a dress and Hato of all people is surprised at how naturally he acts the part.
- Accidental Misnaming: Keiko keeps calling him "Watanabe" in Nidaime. The fact that she actually calls him "Madarame" when she is being serious indicates she does know his real name, she just pretends she does not.
- Madarame is actually called this by Saki's friends in the first manga because the name "Madarame" is a very uncommon name and is similar in pronunciation to Watanabe.
- Adorkable: "He's actually kind of moe, isn't he?"
- Butt-Monkey: Almost every club member in Nidaime considers him a sou-uke, pairing him as a bottom with every sort of pairing. He is not pleased with this.
- Chick Magnet: Saki points out that he, of all people, might have the affection of four people: Angela, Sue, Keiko and Hato.
- Clueless Chick Magnet: Ironically, in Nidaime, he gets four people that are interested in him, yet had no clue about it until Kousaka bluntly exposes it to him. Hato was even practically proposing to him (by declaring that he'd like to cook for him every day).
- Cute Little Fangs
- Hidden Depths: A good chunk of the manga deals with his change of attitude and personality. Just contrast beginning!Madarame and end!Madarame (he cooks, and quite well too).
- Hot-Blooded: During the beginning and middle of the manga, much less so towards the end and during Nidaime. He comments himself in Nidaime that he seems to have lost some of the fire and passion he had when he was in college.
- Moe: Lampshaded by one guest comic in the manga .
- Kouta Hirano called him the most moe character in Genshiken.
- Nerd Glasses: Lapses into Scary Shiny Glasses on occasion.
- Never Live It Down: In Nidaime, Saki reminded everyone that Madarame had a stash of S&M videos (of 3D girls). That's right, years after that chapter was published, Saki still remembers.
- Not So Different: He realizes, after Kasukabe pushes him into getting a nicer outfit, that focusing on fashion isn't much different than buying doujinshi, down to the fact that price isn't always an indicator of quality.
- Proud to Be a Geek
- Serious Business: He will spend food money on manga. This behavior is admired by the others.
- What really impresses his peers: he NEVER looks at price before he decides to buy a doujinshi.
- Uke: So far, every Yaoi Fangirl that comes across him can't stop seeing him as one (except Ohno briefly, but she came around).
A freshman when the series begins, she forms a Beta Couple with Kosaka from the first chapter. While she is at first repulsed by the Genshiken and tries to destroy the club (or at least Kosaka's association with them), she gradually becomes more comfortable with them and falls into the role of the Dungeon Masters Girlfriend.
- Be Careful What You Wish For: In the first half of the original manga, she regularly talks about getting the Genshiken shut down, and she even discusses at one point what would happen if she were to set fire to some of the materials in the clubroom. Almost immediately after the latter, she accidentally does with a cigarette, which destroys some of their collection and gets the club banned from their room for a semester. The guilt over all this leads to the below Heroic BSoD after one too many What the Hell, Hero? speeches.
- Berserk Button:
- She really hates it when someone calls her an otaku.
- Making her cosplay does this to a lesser degree.
- One that comes up in an omake is making fun of her name. She was named after a beloved grandmother, and she will not abide by having it questioned.
- Clingy Jealous Girl: Though she outgrows this more and more as the series progresses.
- Deadpan Snarker
- Deuteragonist: She's as much the protagonist as Sasahara is.
- Fish out of Water
- I Have This Friend...: She uses this to ask about her relationship with Kōsaka. She's spotted right away.
- Heroic BSoD: After accidentally burning several of the club's collection and it looks like she feels no remorse over it, Madarame gives her a massive chewing out. She breaks down crying upon revealing that she indeed feels horribly guilty about what happened and hadn't been able to light a cigarette since because the incident had caused her to develop a fear of fire.
- Jerk with a Heart of Gold: She is often very rude to both strangers and friends and claims she'd rather see Genshiken get taken down, but she genuinely goes out of her way to help whenever she sees that they're in trouble.
- The Fashionista
- Nerd Nanny
- The Nicknamer: She calls Sasahara "Sasa-yan", and Kugayama "Kuga-pii".
- Not So Different: She'll deny being an otaku, but she does finds things in the club that she likes, even asking Madarame if they have more of the manga she'd been reading in the club room.
- Only Sane Woman: Often played this role in the first season.
- Vitriolic Best Buds: Her relationship with the club as a whole is entirely bipolar by the middle of the series.
- What the Hell, Hero?: Is on the receiving end of several, namely breaking Kanako's model figure and setting fire to several boxes worth of the club's books. Despite both of them being accidents, she's accused of having done them on purpose.
Joins the series pretty early. Has a love of cosplay and takes over the club near the end of the series.
- Beware the Nice Ones
- Buxom Is Better
- Cosplay Otaku Girl and Yaoi Fangirl (especially fond of Bara Genre)
- Gag Boobs
- Rapunzel Hair: Useful for her cosplay.
- Shipper on Deck: Has moments where she seems excited by the prospect of Saki and Madarame being together. Not too mention the cosplay pictures of Saki she tried to give Madarame. In an omake she also reveals (while drunk) that she thinks Saki would be "so much happier" if she dated Madarame. She also later says she likes the idea of Angela and Madarame together. While most of the club was in on it, she also was instrumental in pushing Sasahara and Ogiue together.
- Shrinking Violet: She's extremely shy except when cosplaying. Or when you trigger her otaku side. By Nidaime though, she's gotten better.
Joins about midway through the series, swiftly becoming the character most often in the spotlight. Unlike most of the Genshiken, she is very hesitant about being an otaku as a result of a trauma inflicted on her in middle school.
- Ascended Fangirl: She gets her manga serialized in Nidaime.
- Character Development: She does from an intensely self-loathing otaku who was afraid to ever put her art out there to a much more confident, less self-destructive leader who becomes a published artist.
- Expressive Hair
- Good Eyes, Evil Eyes: While she is initially self-loathing and cynical, her eyes don't reflect light. When later she begins to open her heart to other people, her eyes begin to shine.
- Ms. Imagination: The extent to which was revealed in an omake - in about a minute, she came up with a rather elaborate scenario for her SasaharaxMadarame yaoi idea.
- Nerd Glasses: She switched to contacts when she went to college, but she uses her old glasses as a disguise sometimes.
- Shipper on Deck: She says she thinks Sue would be a good match for Madarame.
- Tohoku Regional Accent: Though she hides it by speaking Tokyo dialect, it slips out under stress.
- Tsundere: Used in the description, at that!
- When She Smiles: In the new manga. It's when she receives the call that her manga's going to be running in Afternoon.
- Yaoi Fangirl: Oh yes.
- Will They or Won't They?: With Sasahara. They did.
Tanaka is perhaps the most skilled member of the Genshiken. He can design Cosplay outfits with ease (he is even able to tell someone's measurements by just looking at them in a bathing suit) and he is also an excellent model maker. He's arguably the most down-to-earth member of the group.
- Cosplay Otaku Guy: Before Ohno joined, he wore his own costumes more often, and he's still dedicated to cosplay afterwards.
- Eyes Always Shut: And his English VA in Season 2 is the new voice of Brock!
- Nice Guy
- Serious Business: He takes Cosplay and Gundam models very seriously.
Kugayama is a member of the Genshiken with aspirations of becoming a manga artist. However, he's poorly motivated and very asocial, which makes him a difficult person to deal with. After graduating, his appearances with the club become more infrequent.
- Brilliant, but Lazy: Kugayama is a skilled artist, but rarely finishes anything he starts. This causes a lot of friction between him and Sasahara when the deadline for material submission for ComiFes is rolling around.
- Demoted to Extra: After he gets a job.
- Gentle Giant: Tall, huge, fat, and so shy he even finds it hard to talk to a cashier.
- Speech Impediment: Stutters.
- Stout Strength: He shows it off in the novel.
- Ambiguous Disorder: Whereas most of the other club members generally don't have much trouble functioning in public, Kuchiki seems mentally unable to grasp the basics of social interaction and what is acceptable in public.
- Dirty Old Man: A young version.
- Creepy Crossdresser
- Determinator: He spent an entire day shopping for doujins without food or water.
- The Friend Nobody Likes
- Harem Seeker: The smile he gets when sees he was the only guy in the club at the start of Nidaime could be described as pure bliss.
- Proud to Be a Geek: And extremely shameless about it.
With the continuation, and the graduation of most of the old cast, several new members were introduced in chapter 56,
all mostly female.
Better known as Sue. Promoted to main cast in the continuation, but actually became a member near the end of the original manga. A friend of Ohno's from America who visited once for ComiFes with Angela and grew attached to Ogiue. Now an exchange student, she speaks almost entirely in anime quotes.
- Ascended Extra
- Clingy Jealous Girl: Unwittingly became one in regards to Madarame.
- Cosplay Otaku Girl: Walks around campus in cosplay and willingly acts as Ohno's dress-up doll.
- Foreign Exchange Student: She is technically neither an exchange nor a transfer student, just a freshman who came from America, but nevertheless is a similar source of confusion and comical situations, with her limited knowledge of Japanese language (majority of her lines being quotes from manga and anime), eccentrically extrovert (although good-hearted) personality, creepy child-like face and exotic looks (long blond hair and blue eyes). And, of course, being an Occidental Otaku.
- The Gadfly: Unlike Kucchi who is simply shameless, Sue is genuinely amused when she gets people angry or flustered and blows her own top when she fails to do so.
- Hidden Depths: Played with. She does have a regular grasp of Japanese outside of anime and manga quotes. However, her character remains impenetrable and most of the 'revelations' during her spotlight story with Ogiue were the latter's impressions.
- Luminescent Blush: Gets those in Nidaime whenever Madarame is around.
- Obfuscating Stupidity: Her knowledge of Japanese is much stronger than she initially lets on - she only slips up once in the original series, and even that took Ogiue a moment to notice.
- Nonstandard Character Design: Arguably even more so than Kucchi. Her distinctive eyes have yet to appear on any other character.
- No Social Skills: Personal space means nothing to her as she messed with Tanaka's model set without permission, reads porn in public and follows Ogiue around.
- Occidental Otaku: Hardcore enough that the only one that can keep up with her to play off her references is Madarame most of the time.
- Older Than She Looks
- Phenotype Stereotype
- Speaks in Shout-Outs: And some of them are downright obscure or bizarre. Despite this, most of them suit the situation pretty well, amazingly enough.
- Shipper on Deck: Ships Hato X Madarame. Although she became interested in Madarame herself before actually getting with him in the penultimate chapter.
- Vague Age
- Yaoi Fangirl
Cross-dressing yaoi fan who is the very picture of a shy, demure, fashionable girl. However, she is a he. Became the main focus in Nidaime, along with Madarame, as his issues take up a good chunk of the manga's frame time.
- The Ace: at least in Yajima's eyes in the second episode of the Nidame anime
- Ascended Extra: Since the mid-60 chapters, he's pretty much become the main character. Highlighted by the opening animation of the Nidaime anime.
- Attractive Bent-Gender
- Camp Straight: Though veering towards If It's You, It's Okay territory with Madarame.
- Have I Mentioned I Am Heterosexual Today?: He does this whenever anyone suggests he might be gay, or at least Bi.
- Nice Hat: Hato wears a rather stylish trilby & avoids crossdressing when trying to distance himself from the rest of the club in episode 13.
- Shipper on Deck: He seems to support Madarame X Sakinote , even though he knows there is little chance of it actually happening.
- And his inner girl ships him with Madarame.
- Shrinking Violet: Hinata-level shy when in-character; he barely speaks up.
- Split Personality: Apparently his female Yaoi Fangirl persona hovers over his shoulder, 'helpfully' supplying shipping suggestions and pointing out good situations. In the nude.
- Stupid Sexy Flanders: In one scene Madarame has a need to tell himself: "He is a guy. A guy."
- Wholesome Crossdresser
- Yaoi Fangirl: Sue calls him a fudanshi (rotten boy).
Energetic and shameless Yaoi Fangirl.
- Covert Pervert: Minus the covert part.
- Genki Girl: Radiates cheer and good fun.
- Mundane Made Awesome: Is more stoked about almost anything than the other members.
- Older Than She Looks: Chapter 68 reveals that despite her youthful appearance and being shorter than most of the cast, she's really 20 years old.
- Otaku: Mad about Sengoku Basara and her favourite pairings. Interestingly, she also highlights the relatively new phenomenon of "what's fun is fun" otaku, contrasting the old "otaku is an identity" like Ogiue or Madarame.
- Ronin: She used to be one.
- Shipper on Deck: Seems dedicated to creating events between the new members, like Yajima and Hato. She also thinks Keiko and Madarame would be good together.
- Wall of Text
Rika's younger sister, she is into playing basketball and is a paedophile.
- Attractive Bent-Gender: Yajima certainly thinks so.
- Bifauxnen: Looks enough like a guy that she can easily fool others in thinking she really is a guy.
- Big Little Sister: She is Rika's younger sister, but is taller and looks older.
- Gentle Giant: Seems to be a lot less aggressive than her older sister... until her older sister demands violence.
- Huge Schoolgirl: By far the tallest of the Genshiken's actual members with her basketball physique.
- Younger than She Looks: She is Rika's younger sister but she looks like the older of the two.
Sour and sardonic Yaoi Fangirl. Prone to pouring cold water on everyone's expectations.
- Expy: Looks like a wider, female Sasahara; could be seen as the Sasahara/Ogiue equivalent for this 'season'.
- Green-Eyed Monster: She is very jealous of Hato, mostly because Hato is not only more feminine than her, but also because Hato can also draw better than her and knows Judo.
- Grumpy Bear
- Hidden Depths: Is shown to be laid-back and well adjusted when accompanying her friend Mimasaka.
- Only Sane Woman: Defaults to playing this character whenever the Genshiken does something unexpected but she usually opens up in short order. Which is why she was chosen as the new president at the end of the series
- Shipper on Deck: She ships Hato and Madarame, even though she herself has feelings for Hato.
- Stout Strength: Was able to escape from being restrained by the athletic Risa and seems to have become the club's erasing specialist, which she herself regards as a job needing strength.
- Straight Man: Right from the start, acts as the damper on Yoshitake's enthusiasm.
- Tomboy and Girly Girl: Yajima's big, stocky and plainly dressed; Yoshitake's petite, frilly and cute.
- More obvious with Mimasaka who isn't half as Proud to Be a Geek as Yoshitake is.
The closest thing the Genshiken had to an antagonist. Haraguchi claims to be part of both the Genshiken and the Manga Club, but he has a habit of badmouthing both of them and getting on everybody's nerves due to his condescending attitude. However, he has a lot of connections with semi-professional manga artists.
- The Friend Nobody Likes: See below - absolutely nobody wants to spend time with him. In fact, it's made pretty clear (both in how little time he shows up with the Genshiken and in discussions with manga club members) that all parties do their best to avoid doing so as much as possible. That said, he has a lot of connections. While everyone thinks he's an asshole who would just take all the profits for himself, everyone is sure that he could easily get a dozen quality doujin artists to contribute to something to be sold for ComiFes.
- Jerkass: If there's one thing everyone in the series can agree on, is that he's an asshole.
- Sitcom Arch-Nemesis
- Smug Snake
The First President
The First President of the Genshiken is a mysterious character who seems to have no presence whatsoever, but at the same time seems to be omniscient of what goes on at the College. He hands the presidency to Madarame in the second volume of the manga in order to finish his doctorate thesis.
- Black Eyes of Evil: Without the evil part.
- The Chessmaster: It's implied that he uses the Genshiken as subjects for his senior thesis. He may have hidden cameras in the club meeting room.
- Maybe Magic, Maybe Mundane: It is never explained whether his seeming omniscience and ability to sneak around is magic or mundane in nature.
- No Name Given
- Older Than He Looks: It's heavily implied he had been president of the Genshiken since 1987, and the series takes place in the mid-2000s. He looks like he could be in his mid to late 20s at the oldest.
- The Omniscient
- Stealth Hi/Bye: It really freaks out the other club members (specifically the girls) when he does this.
- It's often accompanied by a Scare Chord in the anime, just to hammer home the creepiness.
Sasahara's little sister, who doesn't share his interests. She is a gyaru. Develops a one-sided crush on Kousaka and joins the Genshiken on a whim, toward the end of the series. In Nidaime, she also works at a hostess bar.
- Annoying Younger Sibling
- Brutal Honesty: Doesn't like it when people keep denying things to themselves and will bluntly tell them about it.
- Character Development: She eventually grows out of her gyaru lifestyle and mellows out to the point of being very casual with the entire group.
- Converted Fanboy: She becomes a fan of Yaoi after Ohno gives her some. She even mentions that she has played some of Kanji's video games he left at home.
- The Fashionista: Even worse than Kasukabe.
- Gyaru Girl: She led a kogal lifestyle in highschool, obviously influenced by peer pressure. She wears heavy layers of make-up on her face, paints her nails and her hair is often styled to whatever is popular at the moment.
- Strong Family Resemblance: Without her make-up, she looks remarkably similar to her older brother.
Ogiue's rival from the manga club who was the person that drove her out of the club and into Genshiken.
- Jerkass: Or at least pretends to be one for a long time.
- Jerk with a Heart of Gold: Or grew one over time. She was instrumental in helping Ogiue and Sasahara get together and she helps the Genshiken directly in the second series. She hasn't gotten used to Sue, though.
- Kansai Regional Accent
- Straight Man and Wise Guy: The Straight Man to Asada.
- Yaoi Fangirl
A member of Yabusaki's posse who usually appears with her and has an unusually minimalistic character design. She was originally a Satellite Character to Yabusaki but was well received enough to have an extended appearance in Nidaime.
- The Gadfly: Joins Sue in pushing Yabusaki's buttons whenever the two are together.
- Hypercompetent Sidekick
- Nonstandard Character Design: Beady eyes with no sclerae or outlines thereof, a permanent Cat Smile and no nose. Simply put, (: 3).
- Straight Man and Wise Guy: The Wise Guy to Yabusaki.
A friend of Ohno and Sue, who visits regularly for ComiFes; Cosplays and is rather flirtatious.
- Bi the Way: In episode 11, after Tanaka tried to dissuade her from reading Kugayama's male-oriented doujinshi, she says it's fine because she likes both girls and boys.
- Chivalrous Pervert: Blatantly wants to sleep with Madarame, but will settle for him picking one of his potential suitors. Or all of them.
- Cosplay Otaku Girl
- Fetish: For glasses and hands. She is interested in Madarame because of these two, and she feels he deserves to be happy and have a girlfriend, but he just thinks she is teasing him.
- Ms. Fanservice
- No Social Skills: She is not ashamed to describe graphic sex in detail. Fortunately for her, not a lot of people understand what she's saying, but it annoys Ohno pretty badly.
- Occidental Otaku
- Phenotype Stereotype
An old friend of Yajima's from high school.