In 3-gatsu no Lion, two characters both serve as foils for Rei Kiriyama, the frequently morose protagonist who is lacking drive in shogi and his life in general. Harunobu Nikaidou is his foil in terms of philosphy and ideals, while Hinata Kawamoto is his foil in terms of general emotional disposition. Their personalities are used to emphasize the traits that Rei himself lacks.
Haruyuki and Kuroyukihime starkly contrast with each other. The former is a fat, short kid who's been a victim of bullies and doesn't have many talents except for gaming, but often proves to be stronger than he initially seems. The latter is one of the top players of Brain Burst, vice president of the school's student council, and highly popular in school, although there are times when she appears emotionally vulnerable and more like the 14-year-old girl she actually is.
Haruyuki and Noumi were both bullied- Haruyuki by Araya and other kids and Noumi by his brother- but while Haruyuki became determined to protect his friends, Noumi turned into a bully himself who was no better than his brother.
Aldnoah.Zero: Two of the show's three main characters, Inaho and Slaine, who are caught on opposing sides of the war between the human factions on Earth and Mars. Inaho is a Child Prodigy from earth who's tactical skills and calm logic get him some serious victories against the martians, and a reputation as a Red Baron of sorts; he never overreacts and always aproaches a situation rationally. Slaine, while originally from earth, is fighting for the Martians and operates mostly on emotion. Even when this seems to work for him, it so far has never failed to come back to bite him. The two characters both want to protect the Martian Princess. Inaho wants to simply because getting her safely back to Mars can end the war; Slaine wants to because he loves her. Inaho has many friends and their respect. Slaine is constantly looked down upon by his peers for his Terran heritage. As the show goes on, Inaho racks up constant victories, while almost everything Slaine does (even when he saves the day) shows that No Good Deed Goes Unpunished.
In Assassination Classroom, Isogai and Asano are divergent foils. Both are skilled leaders and renaissance men, respected by their peers...however, Asano is a total jerk who bullies others into submission and frequently boasts about how superior he is to others. Isogai is a Humble Hero who works alongside the other students, respects their opinions, and thanks them for helping him. (The narrator concludes that Isogai is a far superior leader.)
Karma and Kayano are this as well. They may be Nagisa's closest friends, but they have differences. Karma has been known by Nagisa for a long time and, despite being his psychotic tendencies, is a genuine friend. Kayano, on the other hand, is only known by him for a year and, despite her nice girl image, only hangs out with him to cover up her hatred towards Koro-sensei. While Karma is open with his bloodlust, Kayano hides her bloodlust in plain sight. Lastly, Karma wants to kill Korosensei for fun, while Kayano wants to kill Korosensei for revenge.
Bakuman。 features many characters with contrasting personalities and approaches to manga.
The main characters and Eiji Niizuma form a Technician vs. Performer duo, and the pros and cons of each are detailed at length. The main characters carefully calculate whatever they do, whereas Eiji draws whatever comes to mind, making them best suited to cult and mainstream hits, respectively. Eventually, when launching their fourth and second series, respectively, they begin implementing elements of the other type of series, with Niizuma going cult and the main characters going mainstream.
As couples, Mashiro and Azuki are this to Takagi and Miyoshi. Mashiro and Azuki get engaged in the first chapter, but decide not to see each other again until they fulfill their dreams, at which point they'll get engaged (they end up seeing each other a few times, but they ultimately keep to the promise until they finally succeed). By contrast, Takagi and Miyoshi get married less than halfway through the series, and frequently comment on Mashiro and Azuki's idealized romanticism.
Hattori and Miura. Hattori is more experienced, calmer and willing to engage in long-term planning with his writers, working for months or years to generate a hit series. By contrast, Miura can get personally invested in his work, and he often feels under pressure to get a hit going soon, lest he get fired or transferred.
Moriya and Shiratori. Moriya is under the belief that mangaka should aim for maximum artistic value, even at the expense of popularity. Shiratori, however, sees art as something everyone can enjoy for a small price, and that artists should strive to be popular.
Black Lagoon: Rock and Revy provide an interesting contrast; the hardened, cynical Blood Knight who loves money and the mild-mannered, idealistic, Guile Hero businessman. What makes it notable is that in some ways they gradually switch roles; Revy begins showing a few more heroic tendencies, while Rock becomes much more jaded, seeing his heroics as more of a game.
The reason Choujirou Sakakibe became Yamamoto's Number Two is because he made a conscious decision to become Yamamoto's foil.
Sakakibe: 'As a member of your school, I would only be able to imitate you. The role of a right-hand man should be to compensate for those areas which you cannot address!'
Iba and Ikkaku. Ikkaku is a Blood Knight who refuses to reveal the fact that he knows Bankai to anyone else to avoid having to leave the like-minded 11th Company, even if it means losing a fight or dying. By contrast, Iba chose to improve his kido and leave the 11th Company to become a Lieutenant to please his mother, and is willing to run away or use underhanded tactics to carry out his duties. Iba uses this very contrast to try and make Ikkaku understand why not using his Bankai in battle is wrong.
Ichigo and Ishida, and their fathersIsshin and Ryuuken. Both pairs embody the Shinigami/Quincy contrast and have parallel plotlines. Lampshaded when Isshin and Ryuuken agree they're both lousy fathers, but that Isshin's worse.
Yhwach and Ryuuken. Yhwach is the black-themed First Quincy, while Ryuuken is the white-themed Last Quincy. For all that he claims to hate violence, Yhwach is quite aggressive, abusive, and surrounds himself with subordinates he cruelly mistreats intentionally. For all his protestations of detachment, Ryuuken is genuinely gentle and caring, and distances himself from those he loves for their own protection. Yhwach thrives on wholesale slaughter, Ryuuken has devoted his life to medicine and healing. Between them, they hold the secrets - and fate - of the Quincies in their hands.
Byakuya and Kenpachi. The former is an aloof nobleman, fights eloquently in multiple forms of combat with strategy, obeys the law to the letter, (though he gets better). The latter is a savage Blood Knight who came from the poorest of Soul Society's districts, fights with no regard for technique, and does whatever the hell he wants. When they team up together, they become an unstoppable force.
Kako and Kirie. Both of them are the victims of bullying at their school, but deal with it differently. The highly self-absorbed Kako looks down on Kirie in an attempt to bolster his poor self-esteem, and when the time comes to battle, has a Freak Out over his impending demise and tries to flee. Kirie, however, is selfless and concerned about the well-being of others, but despite being deeply troubled by the fact that every time the pilots win, they're killing an entire universe, is ultimately able to come to terms with his feelings and win his battle.
While most obviously, Lelouch and Suzaku from Code Geass are foils of each other, an argument could be made that Diethard is also a foil to Lelouch, being a Britannain aristocrat who at the beginning of the series expresses a similar dissatisfaction with Britannian society. However, whereas Lelouch is very active in enforcing change (for good or ill), Diethard is more of a cheerleader for change and pretty much joins La Résistance because it seems interesting and midway through R2betrays Lelouch when Prince Schneizel seems to be a more captivating leader. In episode 24 of the series right before he is killed, he is shown enthusiastically supporting Schneizel's plan to nuke cities around the world in order to bring "peace".
Shin Hyuga Shaing in the Akito the Exiled OVAs serves as a foil to both Lelouch and Suzaku. While both Lelouch and Suzaku struggle with a certain darkness, and both at least try to resist giving into it (though they both have plenty of "what have I done?" moments), Shin jumps in and embraces ruthlessness. In episode 3, after seeing how far Lelouch has fallen due to his love for his sister, Shin geasses his adoptive sister and mother, whom he loves, to die. Before that, he gives Suzaku a nice Not So Different speech, where, as always, the telling element is what's different even with all of those similarities.
Spike and Vicious. Spike prefers guns, explosives, and martial arts to outwit his opponents; Vicious prefers to just use his sword. Spike wishes to leave the Syndicate and let time take it's toll, Vicious wishes to return the Syndicate to what he knew.
Spike and Andy. Both are destructive, stubborn, glory-hogging, self-aggrandizing braggarts who are nonetheless extremely competent bounty hunters and they get completely at each other's nerves. Spike has a Cool Ship, Andy has a Cool Horse. Spike prefers semi-autos and dresses like a Lupin III cosplayer while Andy dresses like an actual cowboy. Andy, however, lacks Spike's Dark and Troubled Past and therefore comes across as The Fool compared to the nuances of Spike's blasé attitude.
The title heroine of Cross Ange gets two: Jill is more of a Shadow Archetype, a callous and calculating Fallen Princess who represents what Ange can become if she keeps losing people and things she loves, while Salamandinay is an honorable Warrior Princess who represents what Ange could have become, had she grown up in a normal friggin' society. Ultimately, Ange chooses a middle path.
Two of Future Foundaiton's branch leaders, Munakata and Yukizome. Munakata is an emotionally restrained person who's obsessively dedicated to eradicating despair (or what he considers despair, anyway), even at the cost of his comrades' lives; Yukizome is a expressively passionate diplomat who eventually comes to value her students' wellbeing over the greater good. In their origin story flashback, Munakata joins the Future Foundation because he wants to achieve an ideal, and Yukizome joins because she wants to protect the people she personally cares about.
Enoshima and Kamukura. Both are perpetually bored, analytical geniuses aligned with Ultimate Despair as a way to alleviate said boredom. Enoshima actively enjoys despair; Kamukura doesn't. Enoshima spearheads the efforts of spreading despair; Kamukura prefers observing despair rather than propagating it. Both have someone to love, but Enoshima abuses her sister to feel despair; Kamukura genuinely mourns his deceased Love Interest. In short, Enoshima was able to use her similarities with Kamukura to lure him to despair, but their differences ensured he didn't become the absolute fanatic she was, nor did he stick around.
DARLING in the FRANXX has an example of relationships foiling each other, although neither is portrayed as superior. Hiro and 02 bent the rules to become partners, became lovers almost immediately after meeting each other, and 02 'claims' him with something roughly equivalent to a very savage lovebite that reduces his physical health. Ichigo and Goro's partnership was forced on them by APE, they were unsure of their feelings at first, and Goro punctuates his confession to Ichigo by replacing an emotional keepsake that she'd lost.
In Delicious in Dungeon, Kabru is one to Laios. Kabru is a cynic who tends to believe the worst about people while Laios is a Nice Guy who is rather trusting. Furthermore, Kabru is a talented fighter against humans, but lacks experience fighting monsters while Laios despite being goofy, is an experienced adventurer and an expert on monsters.
On top of being an Evil Counterpart to Goku, at least initially, Piccolo is also this to him. Piccolo is cold and dispassionate, while Goku is fun loving and can be quite emotional when angry or upset. Piccolo is one of the smartest characters in the series, while Goku is quite Book Dumb. Piccolo is the responsible one where Goku can be quite irresponsible even when the fate of the world is at stake. Their roles are slightly reverse during the Buu Saga. Piccolo was willing to give himself to Babidi so Buu would stop slaughtering cities. It was Goku who was rational and pointed out that Piccolo sacrificing himself wouldn't help anyone in the long run.
Goku's older brother, Raditz. Both are overachievers much like their father before them, born low-class yet fortunate enough to become elite by attrition after their race was wiped out. While Goku embraced the gentle heart given to him by his mother and works his entire life to break the limits of his birth, like his father, Radtiz chose to hide behind others stronger than him while embracing the ruthlessness of being a Saiyan, rejecting his mother's kind influence. Also, despite Goku's gentle and kind nature, he maintained his Saiyan pride and spirit, while Radtiz's Saiyan spirit has long been driven out of him despite his claims to the contrary.
Vegeta, his eternal rival. Both are thrill-seeking Saiyan warriors always looking to test, expand, and overcome their limits. While Goku is a cheerful man who cherishes others, greatly values his Earthly upbringing, and was born weak among commoner parents, Vegeta is a rough, arrogant prince who initially cares only for himself, and was born very powerful and heir to the throne of his planet. Through a series of trials and hardships, they gradually influence each other as their rivalry matures from resentment to respect. Goku comes to understand Saiyan pride and Vegeta learns compassion for loved ones.
Cell. Like Goku, Cell loves a good fight, loves growing stronger, and is a great deal more clever than he initially appears. However, while Goku is a lower-class Saiyan who trains hard to become stronger the good old fashioned way, Cell is literally optimized at a genetic level and cheats, consuming others to steal their hard-earned strength for himself. Most importantly, while Goku ultimately rejects his malevolent Saiyan instincts and chooses to live a (somewhat) peaceful life like a human, Cell embraces his evil nature and eventually seeks to fulfill what he believes to be his creator's will by destroying all life in the universe.
Beerus, his eventual divine counterpart. Both are deities who love so many of the same thingsa good battle, food, fun with friends, and sleeping. However, Goku is a hard-working common man who had to rely on his friends' hearts to become a god. He fights to protect life, and he possesses incredible self-restraint and awareness. Whereas Beerus has lived his entire life hovering like a giant above everyone else in his universe aside from his master attendant. His whole job is to destroy to make space for more growth, and his Hair-Trigger Temper and Olympian sense of entitlement make him frightening to be around for most who've met him.
Jiren of Universe 11. While both Goku and Jiren are the aces of their teams and some of the most powerful beings in their respective universes, Jiren attained his great strength entirely on his own, refusing to befriend or even trust others. Conversely, Goku is as strong as he is because of the many friends and allies he's made throughout his life who push him forward and higher up. It was only through this ideological difference that Goku was able to defeat Jiren.
In a non-villain example, Goku to his son Gohan. They are both extremely gifted warriors who represent the peak of their groups. Goku is the strongest pure-blooded Saiyan, while Gohan is the most powerful of all the hybrids. They are both also pure-hearted, fun-loving, have a love for animals and people, and are somewhat naive about the outside world. However, Goku loves to fight and challenged himself, while Gohan hates fighting and hurting people, and won't train unless there is an immediate danger. Goku is Book Dumb and doesn't work to support his family, while Gohan is very well education and has a steady job by the end of the series.
Broly, his fellow Saiyan outlier. Both are powerful Saiyans who ran afoul of the royal family and traditional Saiyan culture, they were kept in the same chamber room after they were born, escaped Frieza's genocide of their planet and people apart from the other Saiyans, they very quickly found themselves dressing and living far outside the Frieza Force/Saiyan Army motif and structure, both are messianic characters, both are recognized as the "legendary Super Saiyan" and both are based on the original Monkey King Sun Wukong. But where Goku lucked into his own self-restraint, became well-adjusted if a bit naive, was born with a ferocious spirit that would eventually earn him the strength to become the first naturally-achieved Super Saiyan in millennia through training, feats, and adversities, looked and lived the part of a common man, became king of his own destiny, and cherishes many loved ones as well as life itself, Broly was born with an uncanny power level and a disconcertingly meek personality causing him to be frightened to tears when subject to continuous loud noises, utterly lost his mind at the first sign of life-or-death trauma as a result, and had to be dressed in attire resembling a regal or holy being that at the same time was used to virtually lobotomize him, and was used as his father's puppet of destruction until his mutant Super Saiyan power burst through and was unleashed in the form of an incredible hulking demon out to kill everything including said father, not even stopping to feel pain unless fatally pierced or torn into.
Turles, his death-skinned doppelganger. Both were born low-level Saiyans who looked exactly alike, led a group of allies, escaped and survived Frieza's genocide pretty much on their own, and became stronger than they were supposed to be as time went on. Whereas Goku became a peace-loving defender of the Earth through a head injury and his mother's influence on Planet Vegeta, typically works for his strength and only siphons power from others by asking for it to take out true threats with the occasional Spirit Bomb, Turles is a calculating, cold-hearted marauder with ambitions of conquering the universe, who achieves most if not all of his gains in power by planting a life-sucking tree into planets that it then proceeds to rot to death, then eating from its forbidden fruit.
After character development, Vegeta becomes this to Frieza. Unlike his former boss, Vegeta learns to care about others and being able to set his pride aside for the benefit of others and his own sanity. By letting go of the past, Vegeta becomes a happier person. Frieza, on the other hand, never learns from his experiences and remains an uncaring fiend even after he is given a second chance at life. He allows his hatred and anger towards Goku to drive him insane, and it's his inability to let go of his pride and the past that drives him to his death, twice.
Gohan to his young brother Goten. They both have many similarities to their father like their pure-hearts, love of animals, and their innocents and fun-loving nature. Goten inherited his father's carefree personality, while Gohan is serious and down to Earth. Goten is quite hyper, while Gohan is very reserved. Goten is allowed to be a child and Gohan was forced to grow up fast because of the constant danger the Earth was exposed to.
Future Trunks have two foils:
Kid Trunks become this to him after the timeline split apart. Kid Trunks is irresponsible, spoiled, playful during battle, and somewhat arrogant. Future Trunks is very responsible, humble, a Combat Pragmatist, and will kill to ensure peace. Kid Trunks is affected by living during a time of peace with both of his parents, while Future Trunks lived After the End where the androids killed all his loved ones, including his father and mentor, Gohan.
To his father. Vegeta loves to challenge himself and fight, even if it means risking the world. Trunks, who grew up in a Bad Future, doesn't care to fight fair or challenge himself, especially when the world is in danger. Trunks is also willing to put the needs of the many before his own desire, while Vegeta only cares about himself and what he wants, at least before character development hits him.
Kid Trunks is a foil to his best friend Goten. They're both sons to some of the most powerful beings in the universe, but while Trunks is born into privilege, Goten is born into a common family that is somewhat poor. Goten is also very silly, while Trunks tries to play the serious one.
The Tartaros Arc seems to reinforce this relationship between Natsu and Gray. The former is directly tied to the dragons of the series, while the latter is tied more to demons. Gray even gets his own Slayer type magic to parallel Natsu's Dragon Slayer magic, Devil Slayer magic which he inherited from his undead father. By the end of the arc, Natsu resolves to kill Acnologia, the dragon responsible for killing his own father, as well as the other Dragon Slayer's dragon parents. While Gray resolves to kill E.N.D., the strongest demon from Zeref's book, the same place where the demon that killed his parents and teacher originated from (who, unknown to him, is Natsu).
Makarov and Mavis, respectively the third and first masters of Fairy Tail. They care a great deal for those closest to them and lead well, but they tend to lead differently, with Makarov leading from the front and Maivis being more of The Strategist. Mavis also comes off as more pragmatic and less averse to casualties than Makarov, whose greatest Berserk Button is people harming his guild. This is best shown in Chapter 505, when Mavis comes up with a plan that could potentially allow Fairy Tail to defeat the Albareth army, but while Makarov thinks the plan could work, he instead opts to use Fairy Law to defeat the enemy at the cost of his own life, simply because he can't bear to see his "children" suffer any longer.
In Fruits Basket, the Honda family (Tohru, Kyoko, and Katsuya) serve as foils to the head of the Sohma family (Akito, Ren, and Akira). When Kyoko learned that she was pregnant, she considered aborting it because she would rather not have a baby than have a baby and give it a miserable life by being a bad mother. Katsuya talks it over with her, and they eventually reach an agreement that she'll have the baby and they'll work together to be good parents and treat the child like a person. After Tohru is born, the three are a close-knit family. After Katsuya dies, Kyoko works hard to be a loving, supportive mother for Tohru. Because of all of this, Tohru grows up to be a kind, understanding person, who doesn't try to force her will on others and tries to make her way through the world. When Ren found out she was pregnant, she uses the threat of an abortion to emotionally manipulate her husband into agreeing to raise their daughter as a boy. When Akito was born, the family began to drift apart, as Ren became jealous of the attention her husband was showing to their kid. After Akira died, Ren became insanely emotionally abusive towards Akito. As a result, Akito grew up being clingy and frightened of the world, which was hidden underneath a controlling and dominating attitude.
Yukari and Erika are fans of Miho and Maho, respectively, although it's implied that Yukari's admiration for Miho is as a person, and Erika's admiration for Maho is mainly due to her association with the Nishizumi school.
In the Little Army manga, Emi is a disagreeable and often brutally honest girl who says whatever is on her mind even if it causes trouble with others (one example is how much she dislikes Miho's older sister for defeating her older sister's team by shooting her flag tank when it went to rescue another). One of Maho's teammates from the manga sucks up to her despite bickering with another member of the team, who believes her doing so is insincere and self-serving.
Yuri Isuzu (Hana's mother) and Shiho Nishizumi (Miho and Maho's mother). Both disapprove of their daughters doing tankery to the point of disowning them, but while Shiho believes Miho is doing it for the wrong reasons, Yuri doesn't like Hana doing it. Additionally, Yuri is, on the most part, a warmer and kinder mother than Shiho, if also considerably more emotional, and argues that Hana's flower arrangement is good as it is in response to Hana's saying that she felt there was something lacking from it, while Shiho considers Miho a disgrace to the family.
Kay of Saunders and Anchovy of Anzio. The former detests cheating and dirty tactics, sending in half of her forces when she learns that one of her subordinates has been intercepting radio communications, which backfired on them to keep things fair, and believes Tankery is something that should be enjoyed and done with sportsmanship. Anchovy takes Tankery as Serious Business and believes winning matters more than anything else, to the point of angrily accusing Miho of throwing away victory when she abandoned her tank to save the crew of another in the last tournament. The contrast becomes more interesting when you consider that in the anime, Anzio's fight takes place off screen, while in the manga, it is shown in its entirety while the fight with Saunders is reduced to the final shot.
Generally, unless they're a Big Brother Mentor, the Char Clone of a Gundam series will usually serve as the foil to one of the main cast. This is most common when the Char Clone is The Rival, but it's not uncommon for a Char Clone to be the Big Bad and also be a foil.
Given that they're both Ace Pilot Newtypes and technical designers with Ambiguous Disorders, poor social skills, and immense Psychic Powers it isn't hard to see Mobile Suit Zeta Gundam's Big Bad Paptimus Scirocco as an older, more jaded, and cynical version of protagonist Kamille Bidan. The difference is in how they deal with their issues—Kamille slowly gets over his problems and learns how to deal with other people, while Scirocco simply develops his Mind Rape skills to the point where he doesn't have to be good at interacting with others.
Jerid Messa is also a foil to Kamille. They're both young, arrogant, ace pilots with a chip on their shoulder and something to prove. Jerid's Jerk Jock persona makes for a marked contrast with Kamille's Insufferable Genius, while his desire for promotions and personal glory, and weak Newtype status, set him apart from the genuinely committed, frighteningly powerful Kamille.
Kyon and Haruhi have such opposing character traits, philosophies, attitudes, etc., that there are significant amounts of Wild Mass Guessing supposing that they are some sort of "foil-power". Or Haruhi chose Kyon exactly because he balances her out. Or opposites just attract. Or they are gods of chaos and order. Pick one, if you like.
However, when you add Sasaki, it looks more like Haruhi and Sasaki are foils whereas Kyon is the middle ground. Haruhi believes in the supernatural and represents chaos but also creativity, freedom, spontaneity and change. Sasaki believes in logic and opposes emotions while representing order but also conformity, oppression and stability/consistency.
Kyon and Haruhi are foils to each other, but their characters are more complex than these arguments suggest, and the foil is correspondingly more elaborate. Kyon is always going on and on about how he'd like an ordinary world, yet he's secretly delighted at the fact that there are aliens, time travelers and espers. Haruhi acts like she's completely convinced that aliens, time travelers and espers exist, but this is a form of denial of her skepticism that they do, and a way of avoiding her disappointment at the ordinariness of her life.
Yuki and Ryōko. The former is an apparent Emotionless Girl who actually does posses deeply held emotions which she is just incapable of expressing; the latter is a bright and cheery girl who, beneath her stepford smile, is completely void of any real human emotions.
Issei Hyoudou and Vali Lucifer. Issei's Boosted Gear doubles his strength every ten seconds while Vali's Divine Dividing halves his opponent's strength every ten seconds (meaning in a direct confrontation, these abilities sort of cancel each other out). Issei is a Lovable Sex Maniac and Harem Seeker and only seeks to become stronger so he can win over girls and protect them (part of his philosophy is that if he is strong enough, he can end conflicts so he can spend more time with girls). Vali is almost completely uninterested in sex (except for a mild fetish for women's butts) and seeks people strong enough to be a Worthy Opponent to him as he is a supreme Blood Knight (he hates peacetime and constantly wishes for war and competition). Issei was born to ordinary human parents and earned his strength through training. Vali was born to noble devil lineage (as a descendant of the original Lucifer himself) and thus inherited vast powers.
For that matter, Issei's and Vali's teams contain several other foils: Kiba and Arthur (handsome and gentlemanly master swordsmen, but the former is of ordinary birth while the latter is descended from King Arthur), Koneko and her older sister Kuroka (both are Nekomata; the former is responsible and initially rejects her heritage, while the latter lives as she pleases and embraces the powers that come with her heritage) and Asia and Le Fay (The Heart to their respective teams, the former is a healer with no fighting skill while the latter is a magician who can both fight and support her allies).
While Issei and Vali are set up as rivals, a less obvious example would be Issei and Raiser Phenex. Both characters lust after Rias, but where Issei is (or used to be) an Ordinary High-School Student, Raiser is a high-class devil from a wealthy family; where Issei wants a harem, Raiser already has one; and where Issei is a weakling who needs multiple doses of Training from Hell to take advantage of his Magikarp Power, Raiser was born with innate talents and a boatload of power, but hardly ever trains. It wouldn't be inaccurate to say that Raiser is everything Issei wants to be... except that he's also a huge Jerkass with an entitlement complex specifically because of that.
Issei also serves as a foil to Tobio Ikuse, the protagonist of the spinoff series SLASH/DOG. Both are ordinary high school students who suddenly awakened their Longinuses (though Tobio is a university student by the time of High School DxD). This resulted in them suddenly being thrust into the supernatural world which they originally had no knowledge of. However, Issei's power enhances his physical capabilities and lets him fight at close range, while Tobio's manifests as a sentient dog that fights independently (though his Balance Breaker turns him into a Wolf Man, allowing him to fight at close range as well). Both of them get powerups because of the ones they love, but Issei seeks a harem while Tobio is devoted to his childhood friend.
Higurashi: When They Cry has Mion (tomboy with a hidden girly side) and Shion (girly exterior with hidden sadist within). Brought up most in Wataganashi-hen and Meakashi-hen.
Inuyasha and Naraku from InuYasha are foils in every aspect. Inuyasha is hot-headed and impulsive, while Naraku is calm, level-headed, and generally avoids fights whenever he can. A more dramatic foil is that, at first, both of them wanted to use the Shikon-no-Tama (Jewel of Four Souls) to become full blooded youkai, but both ended up giving up that idea. Inuyasha gave up that because even though he wanted to grow stronger, he realized that it would mean he would lose his human feelings and likely kill everyone he cared about. Naraku, on the other hand, hated his human feelings but realised he needed them to be able to manipulate and destroy the bonds between people. Lampshaded in the manga itself when Inuyasha observes that while he used his nature to strengthen bonds, Naraku's used his to destroy them.
Tsugawa and Kudo in Japan, Inc.. Tsugawa is your typical ruthless manager, Kudo is the social guy who thinks about the employees.
Part 1 of JoJo's Bizarre Adventure has Robert E.O. Speedwagon and Dio Brando. Both were born to abject poverty, but Dio craved wealth and fortune and was willing to go to any lengths to attain it, including becoming a vampire and expanding his scope to Take Over the World, before ultimately dying at the hands of his nemesis's descendant. Speedwagon, meanwhile, took to petty crime to support his family, accompanied Jonathan Joestar in his travels after he won his respect, and went on to become rich when he struck oil in the desert, his fortunes going to fund research in medicine and science.
Jotaro in Part 3 is The Stoic, in contrast to Joseph's more hammy antics, and the focus is put on a group of True Companions brought together by circumstance as opposed to a pair of rivals sharing a common goal.
Giorno Giovanna from Part 5 is cool-headed and ruthless, a far cry from Josuke's cheerful personality, and he and his allies are members of the mafia instead of just being a bunch of friends avenging a murder like Josuke and Co. And while Josuke's friends ranged pretty wildly, the members of Bucciarati's group are all androgynous prettyboys. And while Diavolo and Kira both want to live in solitude, Kira was fine with his "ordinary life", while Diavolo instead uses his anonymity to rule Passione from the shadows.
The Green Clan in K: Return of Kings are all foils to the established characters, who form an alliance to defeat them.
Nagare, the Green King to Shiro, the Silver King and leader of the alliance, and their Clans. Both have their bases in small rooms where they frequently have conversations over meals around a small table. Both are small clans, although they both have a lot more resources at their disposal. But while Shiro is warm and laid-back, Nagare is bent on his plot, and crosses several lines, including orchestrating the events of the first season, where Shiro barely prevented a major disaster, and at least two people were killed.
Tenkei Iwafune, the Grey King to Reisi Munakata, the Blue King - During their fights, Iwafune basically tells Munakata "Silly Rabbit, Idealism Is for Kids!", and that he should give up on his and his Clan's mission to bring peace and order. Iwafune was once the leader of a large Clan that did a lot of good in the city, but all of them were killed in the Kagutsu Crater disaster when then Red King's Sword of Damocles fell ten years ago. After that, Iwafune became cynical, thinking that the world can't be trusted and must be taken down to a free-for-all where Might Makes Right. Even through losing his Clan and feeling his Sword falling apart, Munakata maintains his focus and intent.
Sukuna Gojo to Misaki Yata and Saruhiko Fushimi. Sukuna is a young kid who started playing Jungle (the Green Clan's social-networking game app) to escape from the boredom and pains of his life. He got enough Jungle points to become a J-rank, meet the Green King, and become an actual Clansman. Though it's only alluded to in the anime and spelled out in the prequel novel Lost Small World, Saruhiko and Misaki were like that at his age as well - they even played Jungle. This is all spelled out in their fight in the end, when Misaki rescues Saruhiko and realizes he isn't a traitor, and they work together to defeat Sukuna, who was too much for them before.
Yukari Mishakuji to Kuroh Yatogami. They trained under the same master (and both still quote his haiku poetry), until Yukari had a falling out with the master and left. In the movie that takes place before this season, Yukari challenges Kuroh to put more of himself and his soul into his sword. He does this by focusing on his devotion to his new King, but he wavers. It isn't until the end of the second season that he manages it.
As the suave second to his King, Yukari might also be considered a foil to Awashima and Kusanagi - check episode 9.
Manabe to Haruka in Kotoura-san. Who better to accompany a mind reader than a guy who says exactly what he thinks?
The two main characters serve as foils for each other: Kuroko, a short, physically weak specialist player and a stoicDeadpan Snarker; and Kagami, a tall, naturally talented power player and a Hot-BloodedIdiot Hero.
The Seirin High School's basketball team and the Touhou High School's basketball team. Both are very offensive teams, but the way the play in a team is the opposite. Seirin relies on teamwork, which makes some of their plays predictable, since they work in certain patterns and they have difficulty to play alone. Touhou throws five talented individuals into a mix who need minimum effort of teamwork to win matches and each player scores points for themselves. Kuroko is a team player who cannot do much by himself, while Aomine is a beast that does not rely on his teammates at all and does everything by himself. Since Kuroko is Seirin's best pass player, Touhou needs to stop his passes rather than Kuroko himself, while Seirin needs to stop the very-hard-to-beat Aomine who never passes to anyone.
Another foil to Seirin is the Yosen High School's basketball club. Both teams have a double ace: Kuroko and Kagami for Seirin, and Murasakibara and Himuro for Yosen; each of them is a foil to one another. Kuroko is small and physically weak, but he became an excellent specialist after intense training and because of his love for basketball. Murasakibara is 41cm taller than Kuroko, is a naturally gifted basketball player, but he claims that he doesn't like the sport and only plays it because he hates losing more. Kuroko believes that anyone can become good if they train hard enough, while Murasakibari believes that hard work is worthless if you are doomed to be bad and that you'll never catch up to anyone who is naturally talented. Kagami and Himuro have a Tiger Versus Dragon theme, with Kagami being a power player who is naturally gifted, while Himuro is a specialist who refined his basic skills to become an excellent player. Seirin is a completely offensive team, while Yosen is a completely defensive team, which is even demonstrated by the heights of their players. Seirin has three small players and two tall members, while Yosen has three giant players and two players with average height.
Reim's Fanalis Corps and the Magnostadl's magicians. The Fantalis has low quality of Magoi so they are unable to perform magic (with the exception of Muu and perhaps Myron) but they have Super Strength and Super Toughness. The magicians have more than average Magoi and can perform powerful spells but have a weak body (with the exception of Professor Myers and Aladdin himself). Each are viewed as the symbol of strength of their countries. The Fanalis represent "the power of the people" while magicians represent "the power of magic".
In Mai-HiME, Shizuru and Haruka contrast with one another. Shizuru is a calm, polite Ojou who is highly popular in the school and in love with her best friend Natsuki, but believes her feelings are improper. Haruka has a Hair-Trigger Temper, her family is Nouveau Riche, she only got twelve votes in the election, and is the subject of possible unrequited love by her best friend Yukino, but implies she finds homosexuality disgusting.
The two leads Medaka and Zenkichi are good foils; Medaka is determined, heroic, and altruistic, but also masks destructive and monstrous tendencies and some levels of cynicism. Zenkichi presents himself as her cynical partner who gets dragged around and merely supports, but he hides determination and empathy which are are a similarly invaluable asset.
Later Kumagawa Misogi is introduced, providing the most prominent antithesis to Medaka and to a lesser extent Zenkichi. While Medaka is the ideal heroine who constantly wins and gains allies, Kumagawa continually runs into failures and never truly wins. In contrast to Zenkichi, Kumagawa continually brings people to his level while Zenkichi works as hard as he can to catch up to the extraordinary people around him.
Tohru and Elma. Tohru is a fire-breathing western style Chaos dragon whose human form has long blonde pigtails and serves as a maid. Elma is an eastern style water dragon in the Harmony faction whose human form has short black hair and works at an office.
Kanna and Saikawa. Kanna is a quiet, reserved dragon girl who is easily liked by her classmates; Saikawa is a loud, boastful human girl who isn't well-liked by her and Kanna's peers.
Kanna and Ilulu. Kanna is stoic child, wears white, was banished by her neglectful parents, and has a female Implied Love Interest. Ilulu is an emotional teenager (that looks like a child), wears black, lost her Good Parents to humans, and has a male Implied Love Interest.
Taketo and Saikawa. Take is relatively reserved and more unsure about his feelings toward Ilulu, and Ilulu is more open about her affections toward him. Saikawa openly displays her affection towards Kanna, and Kanna is more passive on reciprocation.
Monster has several of the side characters with A Day in the Limelight subplot blatantly mirror the protagonist's quest in some way. The village doctor is what Tenma could have become had he married Eva. Richard Braun is what Tenma would have become if he had shot Johan without any question to his past. Milan Kolash is the Tenma who goes through with the murder. Johan also has foils in the form of Nina and Dieter.
In Muhyo and Roji, Muhyo was (and still is) a Brilliant, but LazyInsufferable Geniuswith a heart of gold, while Enchu was a hard-workingNice Guy while they were in the academy. This also applies between Enchu and Yoichi, who was another member of their group of friends; when Muhyo's talent became clear, Yoichi realized that he couldn't hope to catch up to him, but Enchu never gave up, and fell into madness after losing the Executor position to Muhyo soon after losing his mother.
Neon Genesis Evangelion uses the mechanic a lot. The most obvious example is Rei and Asuka - their personalities are diametric opposites in a Red Oni, Blue Oni dynamic, which is further emphasized by their reversed appearances (red eyes and short blue hair, blue eyes and long red hair). Shinji falls somewhere between them in temperament, and so serves as a foil to both. Several scenes draw a parallel between Asuka's and Shinji's relationship and Misato's and Kaji's. Ritsuko contrasts directly with Misato. The series has a Geodesic Cast, with several similar groups set up to compare and contrast.
To an extent, the Angels as a whole are a Foil to the "Humans" that inhabit the Earth. They usually embody and symbolize either a trait that their opposition has in abundance or lacking in, or reveal a trait which they have suppressed. Fitting, since they're literally Humans that rejected our Human Forms which metaphorically took a different Path of Life since before Creation.
Not quite they have different origins, creatures created from the seed of life vs those created from the seed of knowledge. It's All There in the Manual. Even though, originally they were souls of citizens of the same world.
While Kaworu can immediately be identified as on to Rei due to the two of them being Adam and Lilith vessels, he was explicitly designed to be one to Shinji. This gets further emphasized in Rebuild of Evangelion, due to an increased emphasis on their roles as unique Impact triggers, the physical contrast (hair, eyes, reversed plug colors, body language, Kaworu's love for change and Shinji's fear of change, Kaworu's blind trust vs Shinji's mistrust) which are placed in similar circumstances, including rebellion against their manipulative guardians: SEELE and Gendo.
Yato and Tenjin in Noragami. Tenjin is essentially everything that Yato wants to be: beloved throughout Japan with several successful shrines and living a comfortable, good life. Unlike Yato, Tenjin is calm and mature rather than brash and foolhardy. He is well respected and takes good care of his Shinki, whereas Yato at times can barely manage Yukine. However, Tenjin is a lot less merciful than Yato when it comes to dealing with misbehaving Shinki.
One Piece has Usopp and Kuro. Both of them are cowards, but while Usopp, an aspiring pirate at the time of his introduction, is willing to overcome his fears and face much stronger enemies to protect those he cares about, Kuro is willing to betray and murder a young girl and sacrifice his own men in order to retire from piracy.
Pokémon has this as well. Satoshi/Ash is impulsive and governs with his heart, while Shinji/Paul is always more in control and strongly favors cold logic. This was pretty much the basis of their rivalry, mainly with them disagreeing on how it was appropriate to train Pokémon.
Both also represent the viewers/players in different ways. Satoshi/Ash is the adventurer, who learns about the world through his adventures and uses the Pokémon he likes and he puts a lot of effort to support them, even on an emotional level, like the casual players care about their Pokémon they raise through their adventure. Shinji/Paul on the other hand represents the competitive players, releasing Pokémon he deems useless or to weak and put them on intense training without caring much about their well-being as long as their limits are pushed on maximum to unleash their potential. Like real life competitive player, Sjinji/Paul's teams follow specific strategies and his Pokémon fill certain roles to achieve victory for the whole team.
XY(Z) presents Ash with two more foils in the form of rivals Sawyer and Alain. While Ash was certainly no slouch prior to his adventure in Kalos, XY gave Ash a huge buff into a supremely competent trainer with the skill and maturity of a veteran which won him the respect and admiration of beginning trainer Sawyer. In XY, Ash was skillful, innovative, seasoned due to his experiences from previous journeys, and unpredictable in battle which was his greatest asset. Meanwhile Sawyer was a bit naïve, getting distracted easily mid-battle, but at the same time analytical and did things by the book which compensated for his lack of experience and allowed him to grow from a trainer who would regularly get his hide handed to him by Ash on a silver platter into a Semi-Finalist of the Kalos League who could actually defeat Ash and pose him a challenge. Infact he built his entire specifically to counter Ash's Team.
Alain serves as a foil to Ash as a person/character. While XY may have amped up Ash's battling skills, he still remained the good natured, outgoing kid who has an uncanny ability to make friends no matter who they are wherever he goes like always. Meanwhile, while Alain is far from antagonistic, mean-spirited, or anything that makes him seem like a Jerkass, he's very aloof and borderline anti-social and only became friends with Mairin because she insisted on following him, and Ash because he feels like is the only person who can give him an exciting battle. No better place is this shown than the Kalos League where you can see Ash sitting with his friends and happily chatting about when he isn't battling while Alain is standing against a wall by himself just observing the action when he isn't battling. Whenever they were in battle, Ash tended to thank his opponents for the battle and compliment their skill, even one trainer he didn't have to battle but did anyway because he promised he would. Meanwhile, Alain after battle would just simply recall his Pokémon and borderline scoff at his battles, calling his matches boring and leave without giving his opponent so much as a glance being visibly disinterested in everyone but Ash who was quite literally the only reason he decided to participate in the Lumiose Conference in the first place.
Puella Magi Madoka Magica the Movie: Rebellion uses Madoka and Homura's relationship to contrast different kinds of love. Madoka's love is extroverted, indiscriminate and conventionally selfless, an emotion that empowers other people; Homura's love is introverted, fixed entirely on one person and dangerously intense- an emotion that empowers herself. (Note that this does not make Homura evil.) Both girls have essentially the same goals, but different methods of reaching them. Which is why it's really unfortunate that they can't work together.
In Sailor Moon Crystal, Venus is Kunzite's foil. Both were renowned guard-captains during the Silver Millenium; both were sworn to protect a different line of royalty. But when evil (here personified as Queen Beryl) beckoned, Venus upheld her duty while Kunzite abandoned it. One Time Skip later, they're mortal enemies.
Close examination of the 90s anime has shown Usagi and Zoisite to be foils as well as shadow archetypes. Both are childish and impatient, the youngest of their respective groups and in need of the most guidance and completely obsessed with the ones they love. But while Usagi is slowly revealed to be The Messiah, Zoisite showcases the darker side of this personality type, leading to his downfall.
Touka and Momo. The former is obsessed with standing out as much as possible. The latter has grown up while being unnoticed by most people, and has accepted that, but wants to be acknowledged and appreciated most by her friend and senpai, Yumi.
The Miyanaga and Matsumi sisters nicely contrast. The Miyanaga sisters were close in their childhood until a tragedy involving the death of a third girl the two of them were close to, at which point their parents separated, Teru stopped talking to Saki and Teru denied even having a sister. By contrast, the Matsumi sisters are very close, with Kuro protecting her older sister Yuu from bullies, while Yuu resolves to gain back any points Kuro loses so that she doesn't feel guilty.
Hiroe and Kyouko, in terms of playing style, as summed up by Hiroe.
Hiroe: "You see, while I have never started a mahjong game even considering the possibility of losing, Kyouko constantly thinks about losing, even to weaker opponents. She derives her strength from that carefulness. That's Kyouko in a nutshell."
Hisa and Kazue both are talented players who ended up in schools with less-than-stellar teams. While Hisa forgoes going to the individuals for her first two years, wanting to go to the nationals with her team, Kazue sees the individuals as a place she can shine without being held back by "weak" teammates.
Kafuka (the ultimate optimist) to Itoshiki (the ultimate pessimist) in Sayonara, Zetsubou-Sensei. Highlighted even further by Kafuka being The Pollyanna to Itoshiki's Attention Whore tendencies where he does not actually want to commit suicide and she has a fairly troubled past.
Skip Beat! has Erika Koenji and Kimiko Morizumi. Both are spoiled brats with influential families note Erika is the daughter of an important company CEO, and Kimiko's family all work as producers or directors in showbiz. and are always willing to use their family's influence to gain advantages in auditions, gaining important roles and fame more easily. The Lotus in the Mire arc shows their differences. Since her original appearance, Erika has taken Kanae's words to heart and has learned to not rely on her connections anymore, choosing to audition and prove that she can earn a role herself by working hard. On the other hand, Kimiko continues to throw tantrums when things don't go her way and is willing to severely injure her opponents, even allowing for the risk of death, if it gives her a second chance at snatching up a role.
Subaru has several foils in the first series, with the first being Takako Sunohara. Both are exceptionally good dancers for their young age, but Subaru's troubled past has caused her to be more jaded and focus entirely on ballet. Takako has a lot of things to do outside of ballet. Made blatantly obvious when Takako's teacher, who shared the stage with Subaru at one point, compares the two by saying that Subaru's dance was dark and oppressing, whereas Takako's dance is 'warm like the sunlight'.
Later on, there's a bigger emphasis on Subaru and Priscilla Roberts. Both came to America to become professional dancers at a young age and Priscilla was accepted by the New York Ballet easily, eventually getting the leading role in Romeo & Juliette and being a renowned dancer for the past 15 years. Subaru struggled more, belonging to a rather obscure troupe, but her dancing of Don Quixote began to gain her some fame. Priscilla even mentions that Subaru reminds her of herself when younger, wondering if she sees Subaru not just as a rival, but a potential successor. Things become more obvious when both dance the Bolero on the same days.
The sequel series finally brings in Hsu Minmin, a Chinese acrobat-turned-ballerina. She and Subaru both have troubled pasts, suffering certain degrees of parental abandonment, view ballet as their main focus.
In Umi Monogatari, Marin is outgoing and positive while Kanon is quieter and gloomy.
Most of the pairs in The World God Only Knows seem to be designed to be foils of one kind or another. Tenri is passive and shy while Diana is pushy and proactive. Vulcan highlights Tsukiyo's cool elegance and emotional reserve, while on the devil side of things you can make similar comparisons between Haqua and Yukie, Elsie and Keima and possibly even Nora and Ryou. (And between Elsie and Haqua, for that matter.)
In World's End Harem Hino Kyouji, the Number One, is the complete opposite of the series protagonist Reito; Hino accepted the new world where women throw themselves at the remaining men pretty quickly, he is constantly having sex without a care in the world, perfectly happy with a situation where he is treated like a King and the harem is always around to fulfill his wishes; while Reito didnt take the news that all men on earth, including his family and friends, died and now women out nowhere demands for him to become a breeding stallion, and still is looking for his love, Erisa, who has disappeared in the crisis.
The two recurring antagonists of Yu-Gi-Oh!'s Duelist Kingdom arc aren Pegasus J. Crawford (tournament host, Manipulative Bastard, Chessmaster, Gentleman Snarker and Squishy Wizard) and "Bandit" Keith Howard (a Smug Snake and Jerkass who'd be The Brute if he wasn't self-employed). Keith's arrogance, underestimation of his opponents, reliance on beating people up, and his belief that the world owes him something contrast nicely with Pegasus, who plays a much longer game, knows he'll have to work towards his goals, and relies on magic and manipulation over brute force. They do not get along.
Kaiba Seto and Jounouchi Katsuya are foils to each other. Kaiba's signature monster is Blue-Eyes White Dragon while Jounouchi's is Red-Eyes Black Dragon. They also have a hot versus cold dynamic.
Yu-Gi-Oh! ZEXAL has Gauche and Droite (whose names contrast, being "Left" and "Right" in French). Gauche is very Hot-Blooded and his dueling style is aggressive and relies on brute force. Droite is an Ice Queen and her dueling style is passive and relies on weakening and manipulating her opponent. Despite their differences, they care about each other very much and are a nearly unstoppable tag-team.