The Chick: Nagisa (Keet). Gou also fulfills this role in the swim club, being their manager.
Gender-Blender Name: All of them have gender neutral names that are popular for girls. Incidentally, their female manager Gou inverts this by having a name usually given to boys. Rin, Aiichirou and Momotarou join in the Theme Naming as well; while Aiichirou and Momotarou's names are male names, their nicknames "Ai" and "Momo" are used as names for girls.
The strong, quiet protagonist of the series. A second-year student with a strong fixation to water. Was childhood friends with Makoto, Nagisa, and Rin. Has a natural talent for swimming, but does not swim forms other than freestyle.
Affectionate Nickname: Is called "Haru" by Makoto and Rin and "Haru-chan" by Nagisa, when they were kids, Rin and Nagisa referred to him as "Nanase-kun" before they became close enough to him to call him "Haru/Haru-chan".
Ambiguous Disorder: His obsession with swimming and water would be rather unsettling were it not clearly meant for comedy and constant shirtless scenes. He will even strip down to his swimsuit in public in order to step into a fish tank.
Animal Motifs: Dolphins. He even has a dolphin as a bath toy and Nagisa compares him to one.
Character Development: Haruka begins the series depressed and closed-off, essentially relying on Makoto to to make sure he actually goes to school and to communicate on his behalf, but gradually he starts to involve himself in things more and more without having to be coaxed, such as personally helping Rei learn to swim (when at first he was ready to reject Rei over his dislike of water), and since opening up to his team in episode 9, Haru's been much more openly emotional, smiling often and being direct in showing concern or appreciation for his friends. Season 2 Haru compared to season 1 Haru is a perfect example of character development.
Cloud Cuckoo Lander: He likes to swim so much that he spends most of his free time in the bathtub when it's too cold to swim outside. He also has a strange fixation on the school's mascot, Iwatobi-chan.
Desperately Looking for a Purpose in Life: The whole point of Eternal Summer. While everyone seems to be moving foward with their lives, it seems that Haru is only wishing for time to stand still so he never has to step out of High School. Not because he wants to stay a teenager forever, but because he wants to have his friends around always and keep on swimming the way he wants to, being free from outside pressure. As he realizes that his friends are all following their own dreams while he obviously has none, as it appears each time more inevitable that they will soon have to part ways, he completely closes off and lashes out whenever asked about his plans for the future.
Heroic BSOD: He had one in the end of Episode 7, when Rin won their qualifying relay and swore he wouldn't swim with Haru again. He got better after his team gave him a comforting pep-talk message on his phone. And Makoto asleep on the floor waiting for him helped as well.
Hidden Depths: He is a surprisingly good artist; the art club try to steal him away after witnessing his rather impressive poster advertising the swimming club. His detailed sketch of Iwatobi-chan isn't half-bad either.*
Icy Blue Eyes: Fits with his character color. Also goes to show his 'cool' personality.
I Just Want to Be Normal: Says he can't wait to be ordinary in the first scene of him as a teenager. However, when Rin shows up, he thinks being ordinary can wait a while.
Japanese Pronouns: Haruka uses ore ("I, a tough young person"; used primarily by adult males) when referring to himself.
Kindhearted Cat Lover: Though not as openly kind, Haruka has been seen playing with the neighborhood's cat and feeding strays with extra mackerel.
Minor Living Alone: Haruka lives alone in his late grandmother's house, although Makoto does live right down the street. Haruka's parents moved away for work, and his grandmother died sometime later.
No Social Skills: Haruka is nice enough on the inside, but doesn't converse much and usually needs Makoto to speak his mind for him. That and his intense obsession with water sets him apart from others. As the series goes on, he becomes less socially awkward.
Non-Nude Bathing: He has a habit of sitting in the bathtub with his swimsuit on when it isn't warm enough to swim outside.
Not so Above It All: Stoic demeanor aside, he blushes and his eyes widen whenever Makoto mentions a cool new pool he can try out. Also, the near-drowning incident shows us another side of him. See Not So Stoic.
Not So Stoic: Though mild at first he shows signs of being worried over Makoto's fear of the ocean in Episode 5. During the near-drowning incident we see him losing his cool and actually shaking with fear while Makoto is still unconscious. But pulls through it. It becomes more noticeable at the end of Episode 7. He looks so genuinely hurt when Rin says he won't ever swim with him again, causing Haru to become troubled over his own motivations to swim. But by the end of it, Haru does get better thanks to Nagisa, Rei and Gou sending him a worried voicemail and finding Makoto waiting for him to come home. The whole latter half of Episode 9 even shows Haru with far more emotion when he admitted he felt happy to swim with the others. It gets to the point where calling him "stoic" is debatable.
By the last episode he's gone from this◊ to this.◊
Episode 9 of Eternal Summer shows Haru actually angry enough to punch a locker and yell at Rin.
Parental Abandonment: A relatively mild case, but he's alone in his house because his father left for business and his mother decided to go with him.
Second Year Protagonist: When we first meet him, he's already in his second year in Iwatobi. He becomes a third-year in the second season.
Security Blanket: In High Speed!, Haruka admits to himself that he keeps turning to water when feels uncomfortable or when he can't change anything. Like Rin moving to Australia when he was just warming up to him.
Shameless Fanservice Guy: All he wants to do is swim, but at each opportunity, his clothes just so happen to be in the way and he doesn't care where he is when he takes them off.
Shower of Angst: Haru had this after he lost to Rin. With the trope, you know it's bad when Haru doesn't feel good with water. He got better after his teammates gave him a "we're here for you" call.
The Stoic: He is first to be seen as this, but then episode 5 came along...
Supreme Chef: Haru is an excellent cook, and always has been, according to Nagisa. One of the audio dramas follows Haru teaching Makoto how to make mackerel braised in miso sauce; all the while, Makoto continually remarks on Haru's cool competence and air of professionalism as he works. The finished dish (which Haru turns into mackerel fried rice, in the end, as Makoto is a dedicated but somewhat hapless culinary student) is apparently delicious, judging by Makoto's rave review of it.
Technician Versus Performer: Performer to Rei (and to a lesser extent Rin)'s Technician; he doesn't care about entry angles or initial velocity or even improving his time, he just wants to swim. And he's good at it.
In one of the "FrFr!" short movies included on the DVD releases of the series, Rei notes that he has never heard Haru laugh out loud; only Makoto recalls ever hearing Haru laugh, back when they were children. This revelation prompts Rei, Rin, Makoto, and Nagisa to tackle Haru and begin tickling him relentlessly in a Must Make Him Laugh ploy. Haru struggles against their efforts, but eventually bursts out laughing — cue the other swimmers' stunned, blushing expressions, as it turns out that Haru's laugh is heartrendingly sweet and adorable.
Cloudcuckoolander's Minder: He's generally the one to try and stop Haruka from stripping. Established in one of the first scenes, in which he shows up at Haruka's house to see why he's not going to school.
He also knows how to get Haruka to cooperate with their plans when the latter is being stubborn (generally by mentioning an opportunity to swim).
Dark and Troubled Past: He developed a fear of the ocean as a child, as a result of an old fisherman Makoto befriended and his crew drowning during a typhoon. Just some time before, the fisherman gave him the pet goldfishes he wanted to catch from a summer festival, but eventually died even with all the proper care Makoto did to ensure they lived long. However, he copes with that fear because he wanted to swim together with Haruka and the others.
Face Your Fears: He's willing to hide his fear for the sake of the team. When Rei needs saving in the ocean, Makoto hurries out to save him. He chokes up and also needs rescuing, but with the support of his friends he is more confident.
Friend to All Children: He's very good with kids. His younger twin siblings Ran and Ren adore him, and he does a great job as a temporary swimming coach to a group of kids in episode 8 of Eternal Summer, even helping one of them conquer his fear of swimming.
Gentle Giant: Easily the biggest and tallest of the main cast, but definitely gentle.
Japanese Pronouns: Makoto uses ore ("I, a young tough person"; used primarily adult males) when referring to himself.
Kindhearted Cat Lover: During the first scene with Makoto, he greets and pets a kitten. He's later on seen playing with it.
Lethal Chef: The poor guy can't cook at all; the lunches he brings to school each day come courtesy of his mother. In one of the audio dramas, he asks Haru to teach him to cook something so that he can feed the twins while his parents are out celebrating their wedding anniversary. The lesson doesn't exactly go smoothly, and Makoto's rather unappetizing first foray into cuisine (a very salty variation on mackerel braised in miso sauce) only proves salvageable after all on account of Haru's own Supreme Chef skills and quick thinking.
Lovable Coward: Makoto for sure◊. It's not difficult to scare him, as Nagisa knows, but he's easily the most caring member of the cast.
Nice Guy: Easily the kindest and gentlest of the main cast and the person who holds his swimming team together.
Not a Morning Person: His younger siblings have to come wake him up in the mornings due to his tendency to oversleep.
Only Sane Man: It's easy to see him as this when you see what kinds of shenanigans his friends go on.
Not so Above It All: Makoto manages to maintain an air of maturity and steadfastness most of the time, but underneath his peaceful, nurturing surface, he's an outgoing, goofy nerd at heart. When he begins to enthuse over "Super Fusion Doppelganger" (most likely a "Super Sentai" Stance their elementary school swim club did together, by the sound of it) and launches into a demonstration thereof in the first episode, even Nagisa moans that he's being embarrassing.
Perpetual Smiler: His default expression is a good-natured smile, befitting his sweet and friendly personality.
Big Eater: Watch as he makes almost half a pizza disappear in less than a minute!
Book Dumb: Somewhat. He is pretty smart and he has no trouble studying - everyone is very surprised at how badly his grades have dropped - it's just that studying AT ALL evokes bad memories of his middle school years. Thus he avoids it as much as possible and his grades plummet.
Cheerful Child: A male version of this when he was young◊. Turns out he wasn't always so cheerful; he said himself in the drama CD that he used to be a crybaby and was bullied often due to his Gender-Blender Name. If that wasn't bad enough, his sisters forced him into dressing up in girls' clothes and he was often teased to the point of tears. He became cheerful after meeting Haruka.
Dragged into Drag: He has three older sisters and when he was younger, they'd often dress him up in girl clothes and have him wear makeup, even packing one of their swimsuits into his swim bag. It's entirely possible that they still do dress him up since they put another one of their swimsuits in his swim bag when he was in high school.
Dude Looks Like a Lady: Somewhat, his keetness makes him as bubbly as a girl, he's very short in stature for a boy his age, he has a bit more of a feminine face than the others, mainly due to his eyes, and was even dressed up as a girl by his older sisters when he was younger. His Gender-Blender Name doesn't help much either.
Dumb Blonde: Appears to be this based on personality, but demonstrates a more cunning side.
Education Mama and Papa: His parents are very demanding when it comes to academic success, often at the expense of Nagisa's happiness. They enrolled him in a very strict middle school where he did nothing but study, and they only allowed him to transfer to Iwatobi with his friends when they notized how unmotivated and miserable Nagisa was feeling. When his grades in Iwatobi drop, they tell him to quit the swimming club and focus on his studies.
Fun Personified: One of his character songs is about having a fun time. His adventurous attitude is what gets the plot going. This may be because his parents were incredibly strict about his studies back in middle school, to the point that he had nothing fun in his life.
The Gadfly: Often plays around with Makoto and Rei. He's also fond of poking fun at Gou's name.
In Touch with His Feminine Side: His room is... girly, to say the least and he owns a pink cell-phone, apparently being forced to dress up like a girl and wear make-up by his older sisters helped him awaken his feminine side.
Japanese Honorifics: Nagisa refers to everyone with the honorific "-chan", which is used to express closeness, fondness, and affection. "-chan" is typically added to the end of a girl's name, but can be added to a boy's name. Ironically, Nagisa is the only one of his inner circle of friends not to be referred with the honorific "-chan", instead, he is the only one to be given the honorific "-kun" which is basically the same as "-chan" but is typically given to boys, and Rei is the only one to refer to him as "Nagisa-kun".
Japanese Pronouns: Nagisa uses boku ("I, a non-threatening male"; used informally and by children) to refer to himself.
Keet: He is generally energetic, cheerful and bubbly.
Smarter Than You Look: Can be very manic and dreamy, but shows good planning and interpersonal skills. Despite how childish he seems, he can be very mature, and he scored a 98 on one of his exams.
Sleep Cute: He falls asleep on a train and his head rests on Haruka's shoulder.
The picture at the end of Episode 3 has him doing this with Rei.
Something Only They Would Say: After not seeing him for 3 years, Haruka and Makoto recognize him when he addresses them as "Haru-chan" and "Mako-chan".
Static Character: Nagisa remains the same throughout the series, he starts out bubbly and cute and is bubbly and cute consistently through the story, he's also the only one of the main characters as of episode 11 to not have an episode feature his Character Development or past, aside from the brief moments he is seen as a kid in Haruka, Makoto, and Rin's memories. Averted in the second season.
Sweet Tooth: He is extremely fond of sweets, especially anything that includes strawberries or is strawberry-flavoured. He even piles strawberry-flavoured protein powder onto some noodles in episode 8 of Eternal Summer, much to Makoto and Rei's disgust.
Tears of Joy: During episode 12, he cries tears of happiness when the team, with Rin, wins the relay.
An intelligent, serious first-year, originally part of the track and field team, but eventually pulled into the swim team by Nagisa. His medley style is the butterfly stoke.
Adorkable: The trailers made him look like a sort of reserved megane archetype. Not so. Dude goes on hilariously passionate rants about only performing beautiful sports, belly-flops into a pool, and occasionally pole vaults like this. Perhaps outclasses everyone else in this aspect.
Agent Peacock: In the ED, with his bright red feather cap and a rifle. In the show itself, he wears a brightly-colored speedo at first, and in one scene a body suit covered in purple butterflies (his animal theme). He's also even more muscular than the others, and an excellent pole-vaulter (too bad he can't swim.)
Animal Motifs: Butterfly. It's also the only stroke he can do, at least until he's tutored exhaustively in the second season.
Awesomeness by Analysis: He uses Physics to get ahead in Track. However, it's shown that doing this doesn't always help him, especially when he tries to apply it to swimming.
Badass: He's the only one on the team with no swimming experience and chooses to take up butterfly? Butterfly is notorious for being the hardest stroke to learn and master. It's always the last stroke taught to new swimmers, and it's insanely exhausting and requires very precise timing. Turns out it is the only way he can swim for quite a while due to its highly technical aspect.
Bookworm: Shown in more than one scene to be reading a book.
Cool Shades: Wears orange wraparounds with his track uniform.
Crippling Overspecialization: Butterfly is the only stroke he can perform properly. He sinks to the bottom with the other three strokes, and it's really weighing him down in Episode 3 of Eternal Summer. He does improve on it though, thanks to having private lessons with Rin.
The Dandy: A variation; he's not afraid to work out, but he's obsessed with looking beautiful as he does so, which is the reason for his initial rejection of swimming, since in his mind the sport involves a lot of unsightly body undulation and desperately gasping for air. Another reason his choosing butterfly is baffling—along with being ridiculously difficult for a beginner, it's probably the hardest to make look pretty.
Embarrassing Nickname: In the preview for episode 11, Rin refers to him as "Speedo Megane", the "Speedo" part referencing the fact he was wearing a speedo when he first met Rin and "Megane" is the Japanese word for "glasses", so it's a reference to his glasses; Rei was embarrassed hearing this to say the least.
Heroic Sacrifice: Not the death kind, obviously. Instead, he gives up his spot on the relay team so Rin can swim with his teammates again.
Idiot Ball: Episode 5. Despite being a raw beginner who's only just learned to swim, Rei decides to do some extra long-distance swim training alone, in the ocean, in the middle of the night when everyone else is in bed, and does not so much as bother to leave a note about where he's gone. Then a random storm rolls in...
Japanese Pronouns: Rei uses boku ("I, a non-threatening male"; used informal contexts and by children) to refer to himself.
Keigo: He uses very polite language, even when he's angry.
Kirk Summation: Gave a passionate one against Rin in Episode 11, questioning why he decided to do a relay against Iwatobi when Rin swore not to swim with Haruka again.
Large Ham: He tends to be this when he's particularly worked up about something, namely sports.
Sir Not-Appearing-in-This-Trailer: he was not in the original PV, only showing up in the second ad. This means he missed out on most of the giant "SWIMMING ANIME!!!" pre-release hype, and has had much less advertisement than the other characters so far. People who aren't watching the anime probably only heard about the original four boys.
Sixth Ranger: An odd case. According to the cast biography, not only did he recently switch from track to swim team, he's the only person not a part of the original Childhood Friends ensemble, and thus likely to have the perspective of an outsider. It's possible that Rin could fill in the role instead, though, as the same biography points out that his former childhood friends feel as if they don't understand him anymore.
Because of this status he actually shares some different, oddly refreshing, views compared to his team mates. Especially with things related to Rin. His thoughts on Rin aren't tinted with nostalgia, so he's a little harsher in his opinions on Rin after his more Jerk Ass moments. Also, he's the only one to notice and actually feel put out by the fact the team's original goal to do well in the nationals has become related to beating/keeping up with Rin, instead of just having a good time and being proud of what they can achieve.
Smart People Wear Glasses: Played with. He is excellent at deduction, math, and applying formulas, but often acts like an enormous dork at times.
Actually, he can float; he compares himself to a submarine.
Technician Versus Performer: Other characters (including his track coach) point out that he pays too much attention to form, theory, and calculation, and it won't help him improve in either track or swimming. He gets inspired to join the swim club upon watching Haru, who is a performer through and through.
Rin's younger sister, a first-year student. She's attending the same school as Haruka and the others and the Swim Club's manager.
Audience Surrogate: Her immediate reaction to Haruka being shirtless is to avert her eyes and insist that good girls don't stare at half-naked guys, but within seconds she's gushing with starry-eyes over his muscles, and has reacted similarly to all other shirtless swimming guys she's seen since. Considering that the main point of the show is Female Gaze-y half-naked boys, clearly she's acting as the audience here.
Big Brother Worship: It's subtle, but she highly looks up to Rin and frequently displays concern for his well-being. In addition, he has her ideal body type in men.
Cordon Bleugh Chef: In episode 4 of Eternal Summer, she makes a very appetizing-looking meal for the team...but it turns out to be stuffed full of chocolate, strawberry and banana-flavored protein powders. Nagisa is the only one who likes it.
Fiery Redhead: Outspoken and tends to be passionate about things, particularly muscles.
Hair Decorations: The light blue decorations at the base of her ponytail, which are actually two little fish.
Insistent Terminology: She prefers to be called Kou, which is a more feminine pronunciation of her name, but no one does. In Eternal Summer, however, she stops insisting this and refers to herself as Gou.
Team Dad: Despite being female and their manager, she is much more into getting results from the team, like improving their time and following a strict regime, and wants the team to be more ambitious.
Tranquil Fury: There's one occasion where Nagisa calls her "Gou" in the middle of a discussion on club business where she sharply cuts him off with "It's Kou", accompanied by a plastic smile and awkward silence for a couple seconds before she simply resumes the discussion.
Older than They Look: If you saw her standing next to her students while they were all wearing civilian clothes, you would think she was another teenager. Justified, since the first episode we learn that she recently graduated college, so she probably isn't that much older than them.
Porn Names: She went by the name "Marin Nishikujo" during her swimsuit model days.
Reasonable Authority Figure: For example, she sees no problem with the boys sneaking into abandoned buildings, since you're supposed to adventurous and a little reckless at that age.
Sensei-chan: Her students even call her "Ama-chan-sensei".
Haruka's rival and former childhood friend, who went overseas for three years and returned with a different personality. Attends Iwatobi's rival school. He trained in all four swimming styles even as a kid, his best style being butterfly, but his preferred solo medley style is presumed to be free stroke to compete against Haruka.
Always Second Best: Since childhood, he is regarded as second in skill after Haruka, a point that drives him to travel overseas to swim.
He was especially hit with this badly overseas, crippling his self-confidence and his desire to swim.
Aloof Big Brother: Although Gou does worry about his well-being, he's never shown to be at all close to her.
Big Brother Instinct: In the drama CD, however, he does mention that Seijuurou shouldn't call other people's little sisters by their first name without first asking permission. He's talking about Gou, of course. When Seijuurou asks permission to call Gou by her first name (jokingly), Rin cuts him off with "NO."
Another drama CD scene reveals that he's paranoid over Gou going out every Sunday, thinking she has a boyfriend. When Nitori suggests that Seijuurou likes Gou, Rin immediately confronts the captain, who, says he went to see a movie with "the little sister". Turns out, Seijuurou meant he went to the movie with his own sister.
In the anime itself he does occasionally demonstrate concern/affection for Gou, such as walking her back to the hotel she's staying in after it turns out both their schools were training on the same island. Still, Sousuke notices that they're not as close as Gou would like and offhandedly tells Rin to spend more time with her.
Animal Motifs: Occasionally referred to as a shark due to his competitive nature; also resembles one via his teeth.
Anxiety Dreams/Dreaming of Times Gone By: In Episode 7, he had one of Haru being a symbolic representation of the level he needed to catch up, to reach his father's talent and efforts. This follows a memory of his younger self and Gou walking with their father's last rites from dying in a typhoon.
Benched Hero: During The Stinger of Episode 11, Seijuurou removed him from the Samezuka relay because his mind wasn't clear on winning with his team.
Big Ego, Hidden Depths: He may be a huge jerk, but it's later shown that there is more to him than he lets on.
Break the Haughty: After beating Haru and declaring he'll never swim with him again he sees how the team swim together and acts jealous and angry at how they replaced him with Rei, with Haruka being the one who wins the team the victory. He pretty much spends Episode 9 breaking down as a result.
Snapping his goggles strap. The others recognize him after not seeing him for three years when he does something similar with the strap on the back of his baseball cap. This tic is also an homage to his father.
He has a tendency to rub the back of his neck.
Cheerful Child: Used to be, but his behavior changed when he went abroad to Australia and became discouraged when most of his classmates were able to swim faster than him. Haruka beating him when he returned to Japan was his breaking point.
Can't Catch Up: While in Australia, Rin had trouble competing again the other swimmers and felt left out of their league. Rin concluded his efforts were clouded because the relay with his friends was distracting him from his goal. His frustrations were what made him want to quit, but swimming against Haru in the first episode was what reignited his drive to swim.
Dragged into Drag: Rather than be forced to quit the team, he begrudgingly agrees to take part in the maid cafe. Mikoshiba, Nitori, and even his sister all think he wears it well.
Disappeared Dad: It turns out that he died in a typhoon during Rin and Gou's childhood.
Embarrassing Nickname: During Elementary School, Haruka and Nagisa called him "Rin-Rin", and he didn't like it at all when this comes up in High Speed! Rin explains to Haruka that at his old school, he was called "Rin-Rin" there as well and got bullied about it and is scared of being bullied again.
Nagisa calls him "Rin-Rin" once more in episode 12, though he takes it quite well.
Evil Redhead: Subverted in that he's not actually evil, per se, just the rival.
Fair Cop: During the second Ending Theme, he wears a policeman's uniform. Needless to say, he looks pretty good in it.
Green-Eyed Monster: Despite the fact that he initially ignored Nagisa and Makoto in favour of challenging Haruka, he is not happy when he realises that "his" place in the relay team (the butterfly stroke) has been taken by Rei. When he watches the relay, he admires his old friends' trademark swimming styles...but snarls all the way through Rei's leg of the race, considering him unworthy of being in the same team as the other three. Rin seems genuinely taken aback at how much this upsets him, having thought that beating Haruka would solve everything.
Though he gets over it by the end of the season. In the next season he teases Rei when he sees that they're both swimming butterfly, and when Rei asks spends quite a bit of time and effort teaching him to swim other styles.
Hard Work Hardly Works: Travels all the way to Australia to get the necessary training to beat Haruka. When he comes back to Japan to start highschool and beats Haruka, he becomes upset—most likely because Haruka didn't seem to put in his utmost effort (or he just didn't even care that he lost, because he doesn't care about winning or losing). He doesn't fully accept this as a satisfying win because either Haruka went easy on him, or, because Haruka just wasn't devastated by the loss like Rin would have been. Then it's revealed he sometimes returned to Japan every so often, and once challenged Haruka when they both went to see their old club. He lost to him again and then told Haruka he was quitting swimming.
It's also addressed in Episode 4 that Rin has been training much harder and is in better physical condition than Haruka, which in Rin's opinion, makes his win pointless.
Played with in the end of Episode 7, Haru trained to keep going on personal bests before the prefectural tournament, but Rin won in their seed and swore he wouldn't swim with him anymore. However, Haru hasn't been seriously training for years because of the incident in the past when he beat Rin and Rin told him he was quitting swimming. Thought note that Haruka only had a month or so to train, ultimately making this victory hollow.
In Episode 11, he reveals that he blames swimming in a relay for affecting his performance since no matter how hard he practiced, he couldn't get the results he wanted.
Jerkass: After meeting his team mates for the first time in years, he insults Haruka for still hanging out with Makoto and Nagisa, the latter two he doesn't even acknowledge. After an unsuccessful attempt to race Haruka, he takes the trophy they had worked so hard for as children and tosses it aside, saying he doesn't need it anymore.
Jerkass Façade: "Endless Summer" Rin seems quite a contrast to the first season. He's often aloof and tends to stare in disbelief or get annoyed with minor things or anyone being interested in Gou, and... that's about it.
Jerk with a Heart of Gold: As it turns out, he's really not that bad and is actually just depressed that Haruka won't race him again in tip-top shape. And also shows genuine concern about Makoto facing the ocean.
Kindhearted Cat Lover: Nitori observes Rin taking in a stray cat from the rain and feeding it mackerel in the old swim club building. Kindhearted... deep down.
Technician Versus Performer: A mild example of a technician in contrast to Haruka's intuitive performer. He consistently weight trains in order to supplement his swimming skills (and even chastises Haruka about not focusing enough on gaining a stronger build). He also frequently reads books about improving swimming techniques.
In season two he's more like the performer to Sousuke's very strict technician, in that he takes enjoyment in swimming with and helping his friends, rather than believing that the only meaningful thing to do with that time and effort is self-train.
Took a Level in Jerkass: After coming back overseas. It is hinted in his talk with Rei and the end card in Episode 11 that disappointment after disappointment of his swimming combined with being alone in a foreign country was enough to make the once idealistic, cheerful child the jaded teen we see today.
Took a Level in Kindness: After the climax of episode 12. He still shows traces of grumpiness, but he's more like the child he once was.
Shown fully in Eternal Summer; while still be a bit grumpy and his general personality is the same, he is much more openly friendly and nice, smiles far more than his first season self did, actually laughs in some scenes, and is openly supportive towards Nitori and Rei when they need it. He's only ever aloof and hostile towards Momotarou, and that far less than in season one, showing mostly when Momotarou is particularly absurd.
Troubled, but Cute: His attractiveness is commented on in-universe, and most of the anime he can't hide his frustration about his swimming ability.
Tsundere: Even after episode 12, his sister and Nagisa both outright say he needs to be more honest with his feelings. Nitori even calls him one once.
More specifically, a platonic example towards the Iwatobi team. Sosuke points out, when Rin complains about them calling him for a favor, that he might complain, but he'll do it anyway.
Turn Out Like His Father: Rin began to swim competitively because he wanted to live out his father's missed out dream as an Olympic swimmer. His father decided to quit his dream when he married and be able to properly raise his son and daughter, but eventually he died from a typhoon during his work as a fisherman to never live it at all.
Adorkable: Strict captain tendencies aside, he's actually a friendly, dorky guy, especially around Gou.
Boisterous Bruiser: Episode 8 reveals he makes good on his boisterous nature by being a very competent swimmer, setting a new tournament record in his prelim.
Commuting on a Bus: In the second season. He graduates in the first episode, so he's obviously absent from the school and training scenes. However, he still shows up from time to time to check on his old team.
Dark-Skinned Redhead: He has the darkest complexion of all the named characters, with red-orange hair.
Dogged Nice Guy: He has a crush on Gou and even tries to ask her out a couple of times. She doesn't seem interested, though.
Hopeless Suitor: Since he's written out at the beginning of Season 2, there's not much hope for him to actually have anything going on with Gou.
Covert Pervert: The second FrFr! shows that he has a porn magazine lying around his books.
Did I Just Say That Out Loud?: Tends to say parts of what he's writing in his diary out loud with Rin nearby. Given that most of what Nitori writes is about Rin, he's left to stammering denials.
Digging Yourself Deeper: When Rin is annoyed about the joint practice with Iwatobi, Nitori says that the Iwatobi boys all have girly names. Rin, who just happens to also have a girly name, is not pleased.
Does it again in Episode 4, when praising Haruka and saying that success "all comes down to talent". He gets a particularly vicious Rin Death Glare for that.
The Rival: Nagisa's in season 2, as Nitori is beginning to specialize in two strokes like Rin, the second being the breaststroke, and in the opening the two are seen competing against each other in the relay.
In episode 2, Iwatobi and Samezuka have a non-official relay against each other at the revival of the Iwatobi SC, he and Nagisa go against each other in the relay Nagisa's stroke is shown to be faster and more refined than Nitori's, and Nagisa beats him in their leg of the relay.
Game-Breaking Injury: There's been lots of Foreshadowing in the way he uses his left shoulder, but in episode 8 of season 2, Kisumi reveals that he's had a serious injury on his shoulder. In episode 10, Sousuke reveals to Rin that he damaged it in his first year of high school due to pushing himself too hard with increasingly intense training.
Green-Eyed Monster: Even though he never says it outright, Sousuke's brief and far-between interactions with Haru clearly display his intense jealousy of Haru's importance in Rin's life, a position that Sousuke wants for himself.
Jerk with a Heart of Gold: He's a bit gruff and blunt, and he is willing to threaten and intimidate Haru, bu he does so for Rin's sake, and the way he interacts with Rin and Nitori suggests he's not all bad.
Man Hug: Him and Rin have their own version of this which includes faking to punch each other.
Team Dad: Almost everything about his behaviors reflect this in him. From his overprotectiveness of Rin (especially when confronting Haru in ES episode 2 ) to the way he acts around the other Samezuka swim team members. There are even long posts on tumblr about how he wears "dad outfits."
Training from Hell: Deconstructed. Once he briefly parted ways with Rin during childhood, he went off to rigorously train himself so that one day he would compete with him. All that training, however, resulted in him damaging his right shoulder to the point that he'll never be able to swim professionally.
Troubled, but Cute: Invoked through Gou's reaction to his usally aloof and dismissive attitude.
Beetle Maniac: One of his hobbies is catching stag beetles. In Episode 11 he even asks Rin to give Gou a stag beetle he caught for her himself.
Casanova Wannabe: Probably, since during his first appearance he mentions wanting to see cute girls which was the only way Rin could convince him to come to the Splash Fest. And since he does things like this◊, he probably doesn't get many admirers.
Fiery Redhead: He's constantly energetic and doesn't ever seem to calm down.
Whenever he talks to Gou, he has a habit of rattling off random facts about himself, like his hobbies and favourite foods, which is a classical way of presenting onself as a potential suitor in Japanese culture.