Ouran Academy is an Elaborate University High catering to the ultra, ultra-rich. Haruhi Fujioka is a frumpy working class scholarship student, a rarity at the school. While searching for a quiet place to study, Haruhi stumbles on an unused music room which turns out to be the club room for the school "Host Club" — a group of idle rich boys who entertain female clients in a sort of Bleached Underpants version of actual host clubs.After accidentally knocking over an Priceless Ming Vase that's worth far more than a working class student could possibly repay, Haruhi is forced to join the Host Club as an assistant to work off the debt. But after Haruhi proves to be a natural Host and is promoted to full member of the Host Club it becomes clear something isn't quite as it seems...Ouran High School Host Club is a shoujou manga and anime that emphatically plays with the cliches and character types inherent in the genre. It hardly ever takes itself seriously, but at times emotions can run quite high, making for some touching moments among all the silliness. The manga version ended in September 2010. The anime was licensed as part of Viz Media's "Shojo Beat" collection, and the anime was made available in North America by FUNimation in October of 2008 (you can watch it for free on the video section of their website, as well as on their YouTube channel). Both are well worth your attention, even if you're not part of the series' normal demographic.A Live-Action Adaptation began airing July 2011.
Or, well, minor adaptation change. The anime is generally quite loyal to the manga, though things are blown even further out of the water, but a couple of subtle character alterations do stand out - for example, making the twins and Kyouya more sympathetic earlier on and, strangely enough, making Honey less so, as the end of the episode "Chika's Down with Honey Declaration" deliberately inverts the manga chapter's denouement.
Also, bananas and strawberries.
The live action drama has some of this too. Renge is only seen in one episode like in the manga, and the Halloween contest, the Refreshing Point competition at the hostel, the Zuka Club, and Kasanoda are nowhere to be seen.
Parodied in the episode introducing Renge, who thinks that the club members need more angst. She tries to recast Hikaru and Kaoru as basketball players torn between brotherly love and the love of the game, Honey as an Enfante Terrible with Mori as his right-hand man, and Tamaki as a lonesome, stoic Sheltered Aristocrat.
Animal-Eared Headband: Ritsu Kasanoda is briefly shown wearing cat ears as part of his attempt to be less scary. It doesn't work.
Animal Motifs: Tamaki shares a lot of the attributes of a dog (he also is a dog lover), Haruhi is often made fun of by the other members for her apparent resemblance to a "tanuki" (raccoon dog), and the twins again are sometimes portrayed as being as sneaky and "devilish" as cats (which just adds to the humor to their relationship to Tamaki.) And is it even necessary to say what animal Honey is associated with?
With Tamaki, it's especially funny when after his and Haruhi's kiss in chapter 83, he's so happy that he proceeds to subtly lick her forehead, (just like a happy dog would?)
Anime Accent Absence: Eclair and Renge can speak fluent Japanese, despite there being little to no indication that they had been required to learn it. Same goes for Tamaki, as he moved to Japan when he was fourteen, but he at least has a bit of an excuse...
Anti-Hero: Renge tried to turn the "characters" of the Host Club into these in "Attack of the Lady Manager!" to attract more customers.
Anti-Villain: Eclair - while she had attempted to take Tamaki away from the Host Club, she did so out of love, and had decent reasons for attempting so. And in the end, she did let him go save Haruhi.
In "And So Kyoya Met Him", the words "third son" are mentioned quite a few times.
Arson, Murder, and Jaywalking: Ep. 5 had the twins list off complaints against one another. In something of a blink-and-you miss it overlap with Self-Deprecation, their last complaint, spoken in unison: "Your mother wears too much make-up."
Art Evolution: Just compare first chapter Haruhi  to a later flashback of that same scene !
Art Shift: The anime's opening (for the most part) has slightly more stylized animation than in the show proper. Also done hilariously with Tamaki in episode 19 for two brief moments.
Attractive Bent Gender: Haruhi is quite a popular host when she's crossdressing. She also looks better with smaller eyes and boyish short hair than with large eyes and long girlish hair.
Babies Ever After: Not shown in either anime or manga, but the author hints in the final volume that Tamaki and Haruhi are the first out of the Host Club members to have children. Mori apparently got married and had kids too (and he'd be the first to congratulate Tamaki and Haruhi when they became parents.)
The following episode has them going to a real beach, per Haruhi's disinterest in indoor beaches. Of course it's a private beach. On Okinawa. And only because Haruhi doesn't have a passport so they can't go to Bali.
Don't even think about trying to harm Haruhi, Mori, or Honey's Usa-chan, or Honey will tear you a new one. Guaranteed.
It's one thing to dress Haruhi up cutely, but hit on her when an overprotective Tamaki's watching, and God have mercy on your soul.
If Tamaki thinks that you might have hurt Haruhi in any way, you'd best hope there's a camera crew watching or else you'll end up a not-so-tasteful stain in the concrete. Violence isn't good publicity for a host club.
When you come right down to it, don't touch Haruhi. Those boys love her, in their own weird way, and will team up to send you into next week. "Beware the Physical Exam!" is possibly the best illustration of this; when they mistakenly think she's being assaulted, they leave her would-be attacker pleading for his life.
Haruhi hates when people tear her away from anyone, if the outburst toward the main villain is any indication.
Kyouya cares so much about his friends he's not above bitching out Tamaki's father for using Tamaki's desire to see his mother again.
Occurs quite a bit. In the manga, you can see Kyouya say "I thought I wasn't going to appear in this chapter" and others pointing out that they're well aware that they're in a manga. Haruhi also seems to talk to the audience, and the twins refer to "the readers" frequently.
In the third episode of the anime, Tamaki states outright that “this anime is a clearly a romantic comedy” and that therefore “Haruhi and I must be loveinterests!"
Brick Joke: During Kasanoda's flashback in "Mori-Sempai Has An Apprentice!", one of the words that Kasanoda's father is teaching his son to speak to sound more "gangster-like" is "Ma." Confused and furious, Kasanoda gives up in rage, questioning when in the world he would ever need a word like "Ma." Cue the end of the episode, Kasanoda stumbles upon Haruhi (who, for the longest time, he thought was a guy), who's changing in the music room. It turns out she isn't a guy. (See First Episode Spoiler below.) Guess what's the only word that he can say to this discovery?
Bros Before Hoes: Kaoru gives up on his romantic feelings for Haruhi]so that his brother, Hikaru, can realise his feelings for her so that he might learn to grow to be a little more independent.
Catapult Nightmare: The first few pages of chapter 79 involve Haruhi standing in front of Tamaki blushing, and looking at the ground. She then says "Tamaki-senpai... I'm in love with you." (The Squee of many a fangirl was heard.) Tamaki looks stunned, but then goes off saying that he's so happy because he's in love with himself, too! He takes this and runs with it. Haruhi looks mortified, but then she sits up and we find out it was All Just a Dream, much to her relief.
Caught in a Snare: The "net" version of this trope happens in the episode with the test of courage.
Cerebus Syndrome: The manga starts to delve into dramatic territory around the fifth or sixth volume, but tries not to sacrifice the funny. And around volume eleven or twelve, things get even more serious, though the jokes aren't completely gone. This was probably (more or less) of the intended variety.
Charm Point: Mori is an odd case since his Charm Point is another character. When the club tries to instruct a delinquent that a Charm Point can work wonders for one's image, they bluntly point out without Hani around people would see Mori as just a huge scary thug who barely talks, much to the latter's distress.
Chekhov's Gun: Parodied. A large, blinking arrow highlights plot devices until they see action.
Close On Title: The episode about Kaoru and Hikaru meeting Tamaki for the first time, "The Door the Twins Opened", saves its title card for the closing scene, after the twins open the door to the Host Club's room.
Usually Tamaki, but most of the characters have had one of these moments.
Haruhi has also done this multiple times from the beginning: when she broke the vase and found out how much it was worth as well as when she finds out the Host Club followed her to the inn where she was working.
Happens a fair amount to the twins and sometimes Hani and Mori when Kyouya points out something about Haruhi/'s situation. Haruhi can fall victim to it thanks to Kyouya as well herself. Tamaki, of course, is highly susceptible to these same colour failures. Kyouya himself is subjected once or twice when everyone is (such as when Yabu is said to be headed to the special boy's clinic or when Kirimi points out a "reverse harem"), once even having a crack appear in his glasses.
"Lovely protagonists like us are never subject to time~! (author note: there will be no moving up in grades)"
Messed with in Chapter 71 by Honey, Mori and Nekozawa all lament their impending graduation in their own way, to the shock of the Genre Savvy Haruhi. Notably, the cessation of the manga's Comic Book Time coincides with its Cerebus Syndrome reaching full onset.
Senpai, would you please stop growing mushrooms in other people's closets?!
"I'm making a hamster home..."
His father is known to do this as well when he's upset.
Cosplay: As a part of their "job", the Host Club regularly changes their outfits and music room's decorations into various themes (ancient Japan, tropical island, etc), maintaining appropriate temperature by air conditioning - which was, loosely citing Tamaki, "invented specially for those kinds of things".
Creepy Twins: Hikaru and Kaoru. Often eerily reminiscent of (siamese cat pair) Si and Am from Lady and the Tramp. Also more reminiscent of the twins from The Shining... just watch their childhood/coming-of-age episode! Less so in the manga.
Crossdresser: Played with until its stitching ruptured. It's played straight with Ranka and Haruhi, subverted with Benibara, parodied/played for laughs with the host boys (consider that they are thoroughly bishounen and would have no trouble looking like girls in the average anime) and Kasanoda, and (shockingly) played somewhat seriously when Ranka appears without having shaved or made himself up. Oh, and lampshaded when the girls of Ouran talk about how much they'd love to see Haruhi-kun in girls' clothing. Way too much fun.
Cursed with Awesome: Oh, no! I've broken a vase, and to pay off my debt, I have to hang out with a bunch of well-mannered, cultured, downright hilarious, and dashingly handsome guys and meet rich girls who wouldn't give me a second look otherwise? Whatever will I do??? In fairness, the guys might be funny to watch but they could still be quite hard to live with. And don'teven getstarted on the girls.
Cute Bookworm: Haruhi. Although we rarely see her read, it's often mentioned it's what she used to spend most of her time doing, and occasionally still does as soon a she gets her break from the Host Club.
Dark Is Not Evil: Everything about Nekozawa is ridiculously "dark". He lives in a dark Gothic mansion, wears a black cloak, listens to ominous, creepy music, deals with the occult, is surrounded by black roses and even his maid and butler look like vampiric murderers. He's actually a pretty nice guy.
The rest of the Host Club get in Paper Thin Disguises to peep on Haruhi's dates with Hikaru and Tamaki.
They then save Haruhi from the Zuka Club and ruin the date.
Dating What Daddy Hates: As if Ranka didn't have trouble enough with Tamaki moving in on Haruhi before, he's anything else but pleased discovering that the two are a couple in chapter 82. And even less pleased with Tamaki going to America with her. Don't worry, it's totally Played for Laughs.
Different for Girls: Haruhi subverts this early on in the manga, as she is already using the masculine pronoun "ore" by the second chapter.
Discriminate And Switch: When Haruhi didn't take her dad to Take Your Parent To School Day, her dad and his co-worker assumed it was because he's a transvestite. Later, the co-worker brought her dad home piss-drunk due to how upset he was about not being told about the school event, which causes Haruhi to reveal that she didn't say a thing because she felt he was overworked and wanted him to use the opportunity to rest.
Down the Rabbit Hole: Not only does Haruhi compare the experience of being in the Host Club to being in another world, but the door to the music room heavily symbolizes this in several episodes. There is also an episode that directly parodies Alice in Wonderland. By the end, she says that around here, it's hard to tell when she's asleep or awake.
Drop-In Character: Renge, although she's more of a rise-out-of-the-floor-on-a-pedestal character. Lampshaded by Haruhi, who in one episode points out that the mechanism used to elevate Renge seems to follow them around.
Dysfunction Junction: They’re pretty mild compared to some of the lengths this trope can go to, but all of the main characters and many minor characters have major personality quirks because of, or are entirely driven by, bizarre or unhappy childhoods or events in their family history (with the arguable exception of Mori).
The Host Club and Haruhi especially gives Tamaki this in chapter 68 of the manga, making him realize that no matter what happens, if he (unbeknowst to Haruhi) decides to pursue her romantically, the Host Club will not be broken.
To a degree, Haruhi gives this to all the three Suohs towards the end of the manga: Tamaki, his father and his grandmother, by making them aware that the main source behind their family's issues is really that none of them ever talks about their problems between one another.
Episode Title Card: Every episode of the anime opens with one of these and Haruhi's voice reading it out loud.
Except "The Door the Twins Opened". The title card is actually the last thing in the episode before the ending theme.
Everyone Can See It: Subtly in the anime, but much more obvious in the manga. After Haruhi realizes her feelings for Tamaki it's unbelivably obvious to everyone EXCEPT him. Honey and Mori seemed to be the first to notice Hikaru's and Kaoru's budding feelings for Haruhi, as well. Kyouya may have seen it, too.
Evil Matriarch: Tamaki's grandmother, who controls all the resources of the Suoh estate. She has forbidden Tamaki from seeing his mother under threat of cutting off the funding his mother needs to combat her illness, and verbally abuses him and his father.
Expository Hairstyle Change: Initially parodied by Hikaru and Kaoru when they dye their hair pink and blue after a staged fight because they were bored. Played straight later in the manga when Hikaru dyes his hair darker after he and Kaoru have a real fight. This is a big turning point for them and shows that they permanently want to be seen as separate people. They even move into separate bedrooms.
Haruhi's hair is a mess on the first appearance, which adds to her masculine and poor appearance. The Host Club gives her a hairstyle which makes her look boyishly cute. Flashbacks show she used to wear her hair in a waist-length Hime Cut which made her look very feminine indeed. The original cut is later explained away as being a self-inflicted emergency cut after Haruhi got gum in her hair.
And don't pretend you didn't think of Fred and George when you first saw the twins. But this could just be a strange coincidence.
And then there's the entire show itself which seems awfully similar to Revolutionary Girl Utena. Both shows are deconstructions of shoujo anime, they also both have a cross-dressing female lead, a pair of twin characters with incestuous tendencies, a character with the surname Ohtori who's known for being manipulative, similar settings, similar music, and, on top of that, they both use pointing arrows and the slipping-on-a-banana-peel gag.
A lot of the character designs for the leads are also lifted from Bisco Hatori's previous work Millenium Snow.
Fanservice: Lampshaded due to the fact that the entire point of the Host Club is to provide it.
Faux Horrific: Tamaki's nightmare about the squalor that Haruhi might be living in.
Faux Yay: In spades, and often with hilarious results.
Fear of Thunder: Haruhi. Her phobia is so severe it's utterly debilitating and it is one of the few things that is never played for laughs.
Fiction 500: Most of the cast. The Host Club is filthy rich, meaning that if Rule Of Cool allows something, they will simply pay reason to take a hike. One character owns a beach, for example. An indoor beach.
Fireball Eyeballs: The female customers gets flaming eyes when they're really fired up about something - usually a particularly adorable Moe moment involving the hosts. It turns into a somewhat bizarre plot-point during the episodes starring Ritsu Kasanoda, a young Yakuza Boss whose icy glare normally freezes anyone who comes near him. He winds up being Sweet On Polly Oliver, causing all the girls to get fired up about the perceived Yaoi romance, and even when he turns his icy glare on them, their fiery intensity melts it on the spot. "Don't underestimate the flames of MOE!"
First Episode Spoiler: Just try describing the series to someone without giving away the fact that Haruhi is a girl. While it's certainly possible in many languages (including Japanese) the plot makes little sense if Haruhi's true gender isn't known.
Fish out of Water: Haruhi, every time she's confronted with one of the more outrageous aspects of the clubs ultra-rich lifestyle. Conversely, the boys often show fish out of water tendencies when they step out of their world to visit Haruhi in hers. Even uber-cool Kyouya is ultimately perplexed by some of the commoner things at the trade exhibition.
Free Fall Romance In the final episode when Haruhi falls off of a bridge while trying to convince Tamaki not to leave for France and he jumps off after her. It's a slow-motion fall that's quite romantic until the splash.
Friend to Bugs: Haruhi, as implied in episode 8 when she finds a centipete on a crab and, instead of killing it, she simply picks it up and throws it aside. When asked if she could have been easier on it, she said "it takes a lot more than that to kill a bug."
Genius Ditz: Tamaki. Despite being an Idiot Hero, he's second best in his class (only beaten by Kyouya), plays professional piano and can see through a person's problems almost right away (he just can't see his own for the life of him).
Haruhi's parents, Ranka and Kotoko (when she was alive). Although not married, Tamaki's parents appear to have this sort of dynamic despite the situation. Hikaru and Kaoru's parents are also happy together and we're told they eventually have another child, giving the twins the little sister they wanted.
The author states at the end of the final volume that Honey and Reiko, Tamaki and Haruhi, and Mori and his wife are all happily married in the future.
Harem Genre: A rare variation where the protagonist is female and the harem is male.
With Tamaki on two occasions. First time is after he's realized his feelings for Haruhi (reason being he's afraid what it will do to the Host Club if he pursues her), and second time is when he learns how his father went behind his grandmother's back and had her fired.
The last episode of the anime counts too considering Tamaki. If you've read the manga to beyond chapter 80, the similarities between the chapters beforehand and the anime's end is quite striking.
Iconic Outfit: Haruhi's first appearance is a wee bit...unflattering.
Aaand, it has returned~! Haruhi goes back to her frumpy outfit in chapter 76 of the manga to protest the banning of the host club and send a message to Tamaki, who has been forbidden to talk to her. Looking back at chapter 1 with the same outfit it's easier to see some Art Evolution, too.
Alot of this in the serie, though a big one is probably how Tamaki spends a good lot of the show fantasizing about a girly Haruhi and doing his best to transform her into such, and continuously failing, all for randomness and comedic purposes to the viewers/readers. However, as the story progresses and Haruhi finds herself in love with him (while he remains completely clueless to this), she gradually turns more into a woman, all of her own. Benibara from the Zuka club points this out in chapter 82, shortly after Haruhi and Tamaki have become a couple, that she now "totally and utterly looks like a girl". So in the end, Tamaki did succeed in making Haruhi more feminine, it just happened when he wasn't trying to.
In an early chapter, an author note states "I can't see Haruhi and Tamaki getting together." The second-to-last page of the entire series is of Haruhi and Tamaki on their wedding day, with an author note stating "Of course, I think the two will get married."
It's Always Spring: Humorously subverted in that it is always whatever season is most convenient for the plot at hand, especially in episodes entirely indoors. The original creator admits to abandoning a hard timeline in a few chapters of the manga.
Haruhi and her dad's penchant for cross-dressing and Tamaki and his dad's ability to sweet-talk anyone. And the Corner of Woe, along with several other of Tamaki's more eccentric traits (though his father's versions tend to be at least a little more watered down).
Tamaki and his mother appear to have an interest in kotatsu.
Hikaru and Kaoru's mother also enjoys playing games just as they do (she happens to enjoy the "Which one is Hikaru?" game). They also inherited their mother's (and badass grandma's) affinity for fashion design.
Tamaki and his grandmother both appreciate music and historical samurai dramas, this is what brings his grandmother out of her depression and helps her to appreciate her grandson.
In the anime Eclair lets Tamaki jump off the bridge after Haruhi. In the manga Kaoru tells Haruhi he loves her, but he has someone else more important to him that he can't hurt. He steps out of the battlefield and lets Hikaru be the one to fight for Haruhi.
In chapter 76 Hikaru says that this new obstacle in Haruhi and Tamaki's friendship gives him an advantage against Tamaki in winning her heart. Kaoru looks shocked and apalled until Hikaru says he was just kidding and says "Don't you think it would be a waste if I said I don't really wish for this to happen?" It's quite clear he doesn't want to see either of his friends miserable.
In chapter 80 When Haruhi says she's going to be an obstacle to their rescue and that she's having doubts about her abilities, Hikaru tells her that it hurts, but she's the one who knows Tamaki the best and vice versa and because of that, she must go escort him to the airport. Awwwww.
In the final chapter Kyouya strongly implies that he's liked Haruhi for awhile, but valued Tamaki and the club far too much to even think of trying to win her over.
Kotatsu: Tamaki likes these a lot, just ask Kyouya. It must run in the family because Tamaki's mother asks Kyouya if he owns one when he met her on a class trip to France. Kotatsu are often used to symbolize close, warm family relationships, something they both desire very much.
Late Arrival Spoiler: Haruhi is a girl, but given that this is revealed at the end of the first manga chapter and first anime episode, it's not all that surprising that all the blurbs on the back of the manga volumes and DVDs tell you straight away.
Legacy Of Service: Mori comes from a family with a long line of serving the Haninozuka clan. The master-servant bond was dispelled when the families were joined by marriage, but Mori still watches over and protects Honey like a big brother would.
Love Chart: Hikaru makes one in the manga with him, Kaoru, Tamaki, and Haruhi. Renge makes one later on, too (although Kaoru's not included on that one).
Love Epiphany: Quite a few of these in the manga. Haruhi's is rather funny and adorable because until then she was completely Oblivious to Love and at first thought her sudden blushing and flustering around her Love Interest were due to a cold or her heart rejecting her.
The anime doesn't doesn't definitively state whether Haruhi will end up with Tamaki or Hikaru, though it does give some pretty strong hints. And with Kyouya's father saying he likes her for Kyouya too...another relatively strong contender?
Medium Awareness/No Fourth Wall: Just the anime, for Rule of Funny. There are frequent references to the audience, and Haruhi addresses them directly more than once, such as when she asks those viewers with blood type AB to not be offended by something Tamaki says.
Meganekko: Haruhi, though she's only seen wearing glasses for the first half of chapter 1, and even then she looked uncannily like a boy.
Mega Twintails: Hikaru and Kaoru wear their hair this way when they crossdress for one of Tamaki's schemes.
Micro Monarchy: Tamaki and pals meet a princess from a tiny imaginary European country.
Mistaken for Gay: Near the end of the manga when most of the girls saw Tamaki and Haruhi having a close moment. That and they thought Haruhi just liked dressing up like a girl. They find out later on though.
Moral Dissonance: Kyoya pretends to sexually harass Haruhi after the thugs at the beach incident to make her realize how vulnerable she is to boys and convince her it's good to apply some common sense every now and then. Of course, it's generally good advice, but it's rather nasty to threaten sexual assault just to make a point.
It's likely Kyoya was still angry at her for frightening them. And she didn't seem to be getting the point otherwise. Also, Kyoya seems to like, and even play up the rest of the characters' view that he's secretly evil so while it was still really creepy, and kind of a What the Hell, Hero?? moment, it's not exactly out of character.
The whole thing is just ridiculously victim-blaming, whatever excuses you throw at it. Likely a result of Values Dissonance as well. Granted, the group was angry with Haruhi for a) putting herself in danger while trying to rescue someone and b) not calling anyone else in as backup, but still, harsh.
The situation in general was just bizarre. The group fails to realize Haruhi can protect herself, and Haruhi fails to realize that the others were justifiably concerned for her. In the end, only Haruhi learns to trust the club. Of course, we lose a lot of funny moments after the beach incident if the club learns that Haruhi can protect herself, so maybe it's slightlyjustified. Doesn't make it any less weird.
Used for laughs a number of times, such as Tamaki's dramatic declaration that he's going to try instant coffee in the first episode.
Tamaki's preferred way of ordering otoro involves some impressive acrobatics.
Mundane Object Amazement: All the boys in the extremely rich Ouran High School's Host Club are amazed at everyday 'commoner' things that Haruhi does or uses, like instant coffee, and saying things like "Commoners are so clever!".
May, in addition to the Kaoru-and-Hikaru-are-like-the-Weasley-twins idea, be a sort of shout-out to Ron and his fathers' reactions to Muggles (fascination, such as with Muggle money or activities for Ron, and most everything for Arthur).
No Romantic Resolution: The anime lacks a definite ending, though it does imply that Tamaki/Haruhi is bound to happen.
Nose Bleed: In the manga Tamaki gets one of these when he sees Haruhi in a dress during their visit to the beach. Haruhi points it out. Tamaki, being the Idiot Hero, thinks he just bumped his nose and Honey's "first aid" only makes it worse.
No Swastikas: One scene involving the Zuka Club has them in orange military uniforms in front of a Nazi flag, except with the kanji for "woman" instead of a swastika.
Kyouya, to the point that the rest of the host club is scared of him in the mornings. Not that they aren't always scared of him. A side story in the manga shows that on a school day, waking Kyouya requires three alarm clocks and at least half an hour...and it was commented that he was running early that day.
Subverted with Honey. The rumor goes that his family was once in a military complex, and a soldier carelessly woke Honey up, and he BLEW THE PLACE UP, leaving only a bunny-shaped mushroom cloud, killing two entire Green Beret battalions. Of course, this is Tamaki's version of the story. The subversion? Honey was taking a nap during the DAY.
Haruhi. Oh boy, where do we start? When Kaoru told Haruhi he loved her she looked a little confused, probably assuming he meant he loved her as a friend. Haruhi's so oblivious that when Hikaru gets the guts to confess to her he asks "Will you go out with me? And I don't mean accompany me outside! I mean in the shojo sense!" Even then it took Haruhi a few moments to see he was asking her on a date. Even worse, when she suddenly began to blush and become flustered around Tamaki she thought it was due to a cold or that her heart was rejecting her, the idea that she could be in love hadn't even crossed her mind.
Hikaru as well. It takes him a damn long time to figure out.
Tamaki is probably the worst offender, going so far as to think his constant fawning for Haruhi could only mean that he sees her as his daughter.
Obviously Evil: Parodied, subverted and deconstructed with Kasanoda. He has the Face of a Thug, is the successor of a large Yakuza group (and trained to be thus), dresses like a Delinquent and easily aggravated, especially by his appearance and its effect on others. Because of this, he suffers from social isolation despite the fact that he's really a Nice Guy underneath it all.
Mori to Honey - the group even envision them in appropriate period-costumes when explaining the Morinozuka/Haninozuka family relationship. Subverted in that they're the same age.
Tetsuya also comes close to filling this role for Kasanoda; though he's only been with him for a few years, he certainly plays the part.
Shima to Tamaki - in the manga, [she not only helps Tamaki realize what he wants to do with his life, she helps the Host Club get to Tamaki to take him to his mother at the airport. In the anime, she's the one who convinces Kyouya that the Host Club should stop Tamaki from quitting school and and going off to France with Eclair since she thinks Tamaki's mother wouldn't want him to do that.
When a crossdressing female is considered the "normal one" in your club, that's really saying something.
Kyouya would count on certain occasions.
OOC Is Serious Business: In a short bonus, Mori suddenly turns cheerful and talkative, to the point even Haruhi is petrified (along with the rest of the Host Club except Honey.) Turns out it's a side effect if he doesn't get enough sleep.
Opposites Attract: Many. Tamaki and Haruhi, Ranka and Kotoko (Haruhi's parents, who're also scaringly similar to Tamaki and Haruhi...), Honey and Reiko (a member of the Dark Magic Club), Mei and Kasanoda (hinted in the final volume).
Orbital Shot: During Renge's first major confrontation with the male club.
Out Gambitted: Tamaki's father and Kyoya's father, along with their companies, perfect a medicine that cures Tamaki's mother and ousts Tamaki's Evil Matriarch grandmother from her position as chairman of the Suou company. This doesn't really have the effect Mr. Suoh intended, however.
Pac Man Fever: Whatever the twins were playing on their Game Boy Advance SP in the middle school flashback in episode 9 of the anime, it had graphics about on par with the old Game-And-Watch series. Their Nintendo DS game later in the episode isn't much better.
Playboy Bunny: Haruhi subverts this in a bonus chapter of the manga and episode 12 of the anime by being stuffed (almost stuffed in the anime) into an Easter Bunny outfit by the rest of the hosts in desperation for fear that Honey would discover Usa-chan to have been stained upon waking up (which he does, actually, but Mori covers for the hosts).
Please Don't Leave Me: Chapter 80. Tamaki says something like this to Haruhi while on the way to the airport to see his mother after three years.
Race For Your Love: Or rather Race For Your Mother, in a platonic twist. In chapter 80, the entire Host Club including all their customers and the people Tamaki's helped throughout the course of the series ensures that he arrives at the airport in time to see his mother for the first time in three years, before she leaves again.
Recursive Crossdressing: Some of the host club's customers mention that they think Haruhi would look good in a dress.
The twins often suggest a "game" to Tamaki at the least opportune moment (using secret agent code titles) usually to either save the club or impress Haruhi, and Tamaki even pits his own host members as rivals.
The Host Club has their share of actual rivals, such as the school newspaper club and the Zuka Club.
The new transfer student that Tamaki saves from getting kicked by a horse is this.
In the anime, this role was given to Lady Eclair.
Rousseau Was Right: In the end, just like another very popular shoujo manga, all strife between the Host Club and other, "antagonistic" characters is not so much due to any one character being greedy, evil or unreasonable, but rather to tragic misunderstanding of each others feelings that is eventually overcome. Even Tamaki's grandmother is eventually played as sympathetic.
Ruritania: The small European kingdom of Monale, where Princess Michelle comes from.
Scare Dare: School after dark. - It's the guys from the black magic club.
Not to mention the Otori family's heavily-armed private police force that Kyouya dispatched when Honey got lost at the pool.
It was a very large pool.
She Cleans Up Nicely: Haruhi is dolled up and used as bait to lure Kanako and Toru back together in chapter 2. Add makeup and a long, straight black wig, and nobody except the hosts were able to recognize her (though Haruhi had to convince Toru at one point that they've never met).
Shipper on Deck: At the end of the anime, Tamaki's father and Kyouya's father state that it would be nice if they could become friends as their sons are... but they amiably state that perhaps it isn't possible because they each want Haruhi to marry their own son in the future. This doesn't take place in the manga.
Apart from Tamaki, Hikaru and Kaoru in the manga, Haruhi also shares a few moments in the anime with Mori and Kyouya that certainly sparked the interest in some fans. In fact, Honey is probably the only Host Club member with whom Haruhi hasn't shared any borderline intimate/romantic moments in either anime or manga.
Hikaru and Kaoru could count as the definition. Their fans may be as numerous as Tamaki/Haruhi's or Hikaru/Haruhi's, even though both anime and (especially) manga makes it clear that their "twincest" is all an act, and while their relationship is still very intimate, it never goes beyond platonic.
Needless to say, Tamaki and Kyouya have their fans too, probably stemming from how their relationship resembles a typical uke/seme one (or how about when Tamaki gave Kyouya a shoulder massage in the manga..?). The fact that Tamaki sees them as the "mommy and daddy" of the Host Club contributes to this. Funnily enough, Tamaki gets about as much upset when Kyouya is mad at him as he does when Haruhi is.
Some of this between Mori and Honey too, although very little, as the author might have thought it would be squick to many (since they're cousins, and Honey looks like a five year old.)
Towards the end of the manga there's even some between Kaoru and Kyouya, one memorable moment being Kaoru blushing when Kyouya takes his shirt off. Granted he apparently was blushing at the "coolness" of what Kyouya was saying, but the timing of the blush is quite convenient.
Shirtless Scene: Played straight most of the time, but played with when the twins gave out a picture of a topless Haruhi for money — it turns out, her head was Photoshopped on Tamaki's body.
The Rahxephon shoutout has to do with one of the main characters from that series saying Lala... which is the magazine Ouran is published in. Could possibly be a shoutout to Haruhi's seiyuu, too, as one of Maaya Sakamoto's earlier seiyuu roles was in Rahxephon. And the fact that Studio BONES animated both series is also a factor.
Single-Minded Twins: The twins, who zigzag this trope depending on the situation. It's usually subverted whenever the camera focuses on them and played straight for comedic segments and during other character's focuses. They use this as a joke in-universe. They spend so much time together that they know the routine, but when they aren't acting, their real personalities show through.
Played straight with their maids, in the anime. Of their six total lines in the anime, five are delivered in perfect unison and they're always attached at the hip.
Haninozuka Mitsukuni's nickname, Honey (Hani? Huni? Hunny?) seems to be spelled differently depending on what fansub you're watching (or on which Troper is editing the page). The Viz translation uses Honey, which seems to be the official spelling.
Also Kyouya/Kyoya. And let's not get started on his last name. Or Tamaki's.
Stock Shoujo Bullying Tactics: In the first chapter of the manga, Haruhi is targeted by a Tamaki fan, who has her clothes thrown away. In another chapter, the Beribara club members suggest that there will be a 'maidens behind the gym' meeting if Haruhi messes the play up.
Straw Feminist: The Zuka Club is an entire club dedicated to straw feminism. They currently supply the page image for it and take the term "feminazis" to the most literal conclusion possible.
Suddenly Always Knew That: Honey comes out of nowhere and single-handedly beats 20 grown men in SWAT team gear. It turns out he's from a family of martial arts experts. Also lampshaded by Tamaki. Inverted when Haruhi faces off against two thugs at the beach and is promptly tossed off a bluff into the water: Tamaki sarcastically cites this trope while berating her for endangering herself so recklessly.
The opening theme is used in a few places throughout the series.
The show's ending theme also makes an appearance, as the ringtone Hikaru uses to I.D. when Tamaki is calling. When Hikaru is comforting Haruhi in the church (and puts his headset on her) the song plays again.
There's also a slow, waltz version of it used during the closing credits scenes in the final episode.
Toilet Humor: In the manga (also included in the live-action series) the first time the Host Club visits Haruhi's home, Honey goes to borrow the toilet, but ends up running back into Mori's arms in tears at how small it is.
In chapter 55 of the manga, Kyouya is irritated by another set of worries Tamaki gives him involving a class trip to France. As a small revenge he proceeds to tell Haruhi over the phone that Tamaki has diarrhea.
Another one in chapter 62 when Hikaru manages to rile Tamaki up enough to make him shout loudly in front of everyone (including Haruhi) that he never "joy pees" (wetting oneself out of excitedment), "except maybe a few times in the past."
Token Evil Teammate: Kyouya is considered by everyone in the club to be more or less evil, especially compared to everyone else. Even the twins are afraid of him. But he's still mostly a good guy.
True Companions: Tamaki sees the Host Club as a family, to the point of assigning everyone roles within it...with Haruhi as his daughter.** And Kyouya as the "mother," and Mori and Hunny being the couple who lives next door... We wonder if Tamaki notices the Ho Yay or not. The fans sure do.
Twin Switch: And the "Which one is Hikaru-kun Gaaame!!" Haruhi, who has known the twins for the least amount of time, seems to be the only one able to tell the difference.
Twin Telepathy: During the Test of Courage chapter. After Hikaru and Kaoru are separated, Hikaru somehow manages to find Kaoru and explains that he had heard his twin's voice telling him where he was, even though Kaoru had no way of telling Hikaru his whereabouts and the latter could not have found out through someone else.
Twin Threesome Fantasy: As well as the excess amounts of Ho Yay and Twincest, this is part of Hikaru and Kaoru's shtick. They explain that a lot of the girls who sit at their table buy into this fantasy, and they use one of the girls to demonstrate why this idea is so popular.
Weak Willed: Tamaki, of the "easily suggestible" variety. When told by Renge that he's "the lonesome prince" type, he jumps into the characterization without a backwards glance.
What Could Have Been: Originally, the character of Kyouya didn't exist. The reason Hatori created him was because she was told to add seven more pages to the first chapter, hence, she figured she needed an extra Host Club member.
What Happened to the Mouse?: In the anime at least, Tamaki gives up a chance to see his mother, and it's not clear whether he ever does again.
Wrong Genre Savvy: Tamaki thinks that it's a romantic anime in the third episode, so he and Haruhi are the progatonists and the rest of the boys are the "homosexual side cast." Somehow, while being Genre Savvy enough to know they are the protagonists, he seems to be unable to follow that statement to its conclusion: namely, that they are love interests.
Yakuza: Kasanoda, prominently; it's said a few times Ouran students lower on the social rank are there simply due to their family's influence.
Yaoi Fangirl: Renge, and many patrons to the club, especially the twins' customers. They also turn out to be the key to making Kasanoda less intimidating, once he (in on the secret) becomes Haruhi's customer.
Kyoya's sister, Fuyumi, once expressed joy at the thought of "two young men bonding together beneath the stars".
Yuri Fanboy: Notably averted in several cases, especially with Tamaki, though he was mostly worried about his love interest becoming a lesbian.
It is implied that Kyoya and the twins might have planned for Haruhi to kiss a girl, but probably subverted because it was mostly to mess with Tamaki's head.