The problem is that many of the boys at school favour girls who appear and act to be older and sophisticated. Harima's cousin, Itoko, notes that Tenma is actually quite attractive by Japanese standards.
The Matchmaker: Lampshaded in the manga, saying she is only good at matchmaking.
Color Failure: Harima goes pale after a rush to complete one of his manga, in a Shout-Out to a certain boxing manga. Also occurred earlier in the first season when in despair after coming across Tenma happily eating together with Karasuma.
Cool Loser: He's good-looking, strong, athletic and something of a chick magnet in school, but this falls apart because of his antisocial nature and numerous misunderstandings.
Hidden Depths: Badass delinquent who is a talented artist, and a lovesick idiot.
Hot-Blooded: He has a tendency to make loud declarations while something explodes in the background. He would not be at all out of place in a shonen fighter manga.
Hurricane Kick: Not really. Instead, played for Punny Name. When saving Tenma from a thug, Harima yells out this trope, but he doesn't spin around (just performing Dynamic Entry). Instead, this is used to take note on 'What if we shorten Harima Kenji', which becomes 'HariKen', which is how the the English word "Hurricane" is pronounced/spelled in Japanese
Mr. Fanservice: He gets lots of shirtless scenes to show off his ripped body. During the Beach Episode, Eri accidentally walked in on him naked, and for the next few days can't stop thinking of... that.
Not So Different: Although he and Hanai consider each other rivals due to the fact that he is a delinquent and Hanai is a class representative, they've got more in common than they'd like to admit — they're both obsessed with a particular girl (both of whom happen to be sisters), Hot-Blooded and prone to misunderstandings, and have been known to come up with near-identical plans independently.
Paper-Thin Disguise: He dressed up as a fortune teller and neither Mikoto nor Eri were fooled. On the other hand, almost nobody can recognize him without his glasses.
Retired Badass: His love for Tenma has caused him to abandon his delinquent ways.
Satellite Love Interest: Deconstructed. He starts to forget why he likes Tenma in the first place, and also starts to believe his attraction to her is almost compulsive.
Scars Are Forever: He has a scar on his back which he got from saving Tenma from a hoodlum.
Selective Obliviousness: On so many things. He fails to notice Eri or Yakumo's feelings for him, just for starters.
Ship Tease: Gets a lot with Eri, more than a little with Yakumo, and a tiny bit with Tenma.
Stalker with a Crush: He's a rare sympathetic example for a male character, as he's the male lead, and not a bad guy at all, just a lovably bumbling fool for love.
Starving Artist: It got to the point in Z where Eri agreed to finance Harima if he married her.
Vitriolic Best Buds: With Hanai. They argue and fight over everything, and Harima often messes around with Hanai for no real reason, but underneath that there's a rock-hard friendship and genuine trust.
Crouching Moron, Hidden Badass: He easily dodges Harima's punch in front of the curry restaurant. Also when he fights Harima pretty much to a standstill in the later chapters of the manga. Not to mention that he singlehandedly racks up quite a few "kills" in the Battle Royale parody.
Laser-Guided Amnesia: Karasuma abruptly loses his memories, forcing Tenma to leave to the United States to look after him. However, it's heavily implied at reunion that some of his memories are starting to return.
Limited Wardrobe: Most of the characters have a few different sets of clothes. Karasuma is only ever seen in his school uniform.
Maybe Ever After: The final chapter of Z shows a scene of Harima and Eri bringing their child to visit the Tsukamotos and Oji in the hospital, but it is presented in such a way that it may or may not be a certain character (Max, Eri's old friend from Britain) imagining it.
Ms. Fanservice: The author loves to show Eri looking good in uniform, casual wear, bikini, evening gown, and of course, naked.
Eri:[sleep talking] Mikoto, what are you talking about? Whiskers totally fails at life. Harima: Okay, moment over, back to being mortal enemies.
So Beautiful, It's a Curse: All anybody sees of her are her stunning looks, and only her close circle of friends see her for who she is. Everyone else sees her as just a beautiful face, and she has quite the complex about this.
Emotionless Girl: Lampshaded. On her birthday, Tenma asks her to show her smile.
Genre Savvy: And strangely so. She is quick to deduce things, even those that would become misunderstandings (naked-Harima-and-Eri episode, anyone?)
The Gadfly: Edging into Troll territory, she really enjoys messing with everyone. She expertly set up the Culture Festival War, which she secretly taped and edited into a film as her Culture Festival project.
Knife Nut: Manga only. She has a knife for everything. She even keeps a spare one.
Establishing Character Moment: In the episode where we find out about Yakumo's mind-reading ability, every boy is thinking about how beautiful and perfect she is while keeping a straight face. Then Hanai shows up, thinking the same thing — the difference is he actually says it. From the moment we meet him, we know he is honest to a fault.
Not So Different: Although he and Harima consider each other rivals due to the fact that he is a class representative and Harima is a delinquent, they've got more in common than they'd like to admit. They're both obsessed with a particular girl, Hot-Blooded and prone to misunderstandings, and have been known to come up with near-identical plans independently.
Rousing Speech: Lampshaded after the survival games arc. Some of the students have no idea what he's talking about yet they feel excited somehow.
Vitriolic Best Buds: With Harima. They argue and fight over everything, and Harima often messes around with Hanai for no real reason, but underneath that there's a rock-hard friendship and genuine trust.
Weddings in Japan: Mikoto and Yakumo both participate in Western-style weddings, both with Hanai as the groom.
Who Would Be Stupid Enough: When he finds out that Tsukamato (Tenma, but he thinks it's Yakumo) is going to an engagement meeting, he rushes off after them on his bicycle.
Nakamura: Please, they're hundreds of kilometers away. He'd have to be a lunatic— Mikoto: Trust me, you have no idea.
Bishōnen: Subverted. He only looks like one when he gets serious. Otherwise, he usually looks like an idiot.
Brilliant, but Lazy: One of the fastest runners in his class. Moreover, he's an excellent swimmer: his endurance and ability is such that he can keep up with Mikoto in a two-mile swim back to mainland. He can also grapple Hanai into a stalemate. The only thing holding him back is his lack of seriousness.
Chivalrous Pervert: Towards Karen, more so once he discovers that she's actually bustier than her uniform shows. He also tends to gravitate towards Mikoto and Lala, if only because of their bustiness. But however perverted he may be, there are lows that he will never stoop to: upon hearing that Karen's date was bringing her to a shady night club, he immediately went to put a stop to it.
Took a Level in Jerkass: By School Rumble Z, he's become a corrupt businessman who ran against Hanai for the position of mayor and turned everyone against Hanai, including all of his friends, through the use of bribery because he simply could not match Hanai's honesty and promises of reform any other way.
Star player of Yagami High's men's basketball team, who dated Mikoto for a short time.
The Ace: Athletic, good-looking, intelligent, and a great chef to boot. Marred only by the fact that he doesn't come anywhere close to being a major character.
The Comically Serious: Even amid the rest of hi class' antics, he remains stoic, often to comedic effect.
Ensemble Darkhorse: In-universe, he's referred to as a "dark horse". He's not as prominent as the other male characters in the series, although he is among the most athletic students in his class. He's also popular among the girls.
Tenma's younger, far more responsible sister. A sweet, kind and soft-spoken girl who also works part-time at a Cosplay Cafe. She develops feelings for Harima when she starts helping him with his manga.
Somewhat subverted when she first meets Harima: she is able to read his mind somehow (because back then, his only true interest was Tenma), but all she sees is an ellipsis.
Cry Cute: She breaks near the end of the first manga, admitting she wanted to connect with more people and become less of a burden to her sister. In contrast, the ghost (her subconscious), bursts out laughing.
Daddy's Girl: One of the reasons she's attracted to Harima is that he looks like the Tsukamotos' father from behind.
The Empath: She can read minds (literally, she sees thoughts as words floating in the air) of people who like her.
I Want My Beloved to Be Happy: We're not quite sure if Harima ended up falling in love with Eri or not, but Yakumo's thoughts in Chapter 9 of Z that she truly believes that Eri is the only one who can break down the wall Harima has put up around his heart.
The Ingenue: Her telepathy makes her painfully aware of impure thoughts towards her but she is still unaware of how to get into a relationship.
Meido: When she works she wears this outfit. It gives her a cute appeal.
Early-Bird Cameo: She is first seen wrestling a masked Tenma, who volunteered to become Karen's substitute so she can go on her date with Imadori.
Even earlier, she is shown in the ending credit sequence.
Expy: Like much of her class, an Expy for a Gundam character. In this case, Lalah Sune.
Friendly Enemy: Her antagonism toward Karen softened during the show's run.
Hidden Depths: Harry once caught her doing cheerleading routines hidden from everyone's view. When she was doing it in the open earlier, everyone thought she was doing it against her will given her lack of expression.
Hot-Blooded: Rare female example. She shouts nearly everything she says.
Jerk with a Heart of Gold: Tends to be incredibly abusive and callous in response to the slightest provocation, but shows a soft side every now and then, especially towards Karen, her self-proclaimed rival. And to be fair, some of her victims did deserve a beating.
Mommy Issues: She initially hated Karen with a passion because the latter shared the same name as her mother, who abandoned her at an early age.
No Social Skills: Her aggressive attitude tends to scare others away. It doesn't help that she is tall and very intimidating, in addition to being visibly foreign and unfamiliar with Japanese customs. On the flipside of things, she does tone this down during her date with Imadori.
Perpetual Frowner: So much so that Imadori risked getting his ass beat just so he can make her smile.
Rousing Speech: She convinced her team to play against the Outlaw basketball team.
Lara: Why have we been practicing? For honor? For glory? No, for victory!
Class Representative of 2-D. He tends to burst into long inspirational speeches. His father is a diplomat, so he brags he's been to the United States. His younger sister Haruna is a friend of Yakumo. Possesses great charisma and can talk people to doing his bidding quite easily.