Brother-Sister Incest/Anime and Manga

"Haruko's friends, in unison: "Your brother's a pervert!" Haruko, cheerfully: "He is!""
 * The sum of the plot in Boku wa Imouto ni Koi o Suru ("I'm In Love With My Little Sister." Talk about Exactly What It Says on the Tin.)
 * Angel Sanctuary features a romantic relationship between the main character, Setsuna, and his (real, not adopted, foster or step-) sister Sara. Rosiel wanted this with Alexiel, but she wasn't having any of it.
 * Great Mazinger -one of the Mazinger Z sequels- features one instance where incest is avoided due to them being adoptive siblings. Tetsuya Tsurugi and Jun Hono -the Official Couple- were two orphan kids Prof. Kenzo Kabuto took in. They grow up together and technically they are family, but they are not related by blood at all, so nobody seems minding, and the issue is never brought up.
 * In an unusually negative scene, there is a pseudo-incestuous rape sequence in Ayashi no Ceres.
 * It also contains a subversion and plot device of this trope, seeing as
 * Hansel and Gretel from Black Lagoon, even though.
 * Da Capo features another almost-incest relationship between a boy and his foster sister.
 * Dokkoida?! deliberately plays with this trope since Suzuo's Mission Controller, Tampopo, disguises herself as his sister, Kosuzu, to blend into Earth society. The eighth episode in particular parodies this trope to the point of full-fledged Deconstruction: seeing a soap opera using this trope makes all of the Pretty Freeloaders in the apartment the characters live in worry about Kosuzu/Tampopo's relationship with Suzuo—including Kosuzu. Suzuo doesn't notice a thing, and manages to restore the status quo with a Dunno What's Going On, But... speech at the end.
 * Averted in Fist of the North Star when Juuza discovers his childhood sweetheart Yuria is actually his half-sister. They drift apart soon after, having never consummated their relationship.
 * Genshiken pokes fun at this, with Sasahara, who actually has a sister, delivering the quote from the main page.
 * Massively implied in .hack//tasogare no udewa densetsu (epecially in the anime, where it's played mostly straight, moreso than the manga, where it's largely played for laughs) between protagonists Shugo and Rena that the series has become derisively known among critics as ".hack//Twincest".
 * Koi Kaze plays this trope straight with two blood siblings who haven't seen each other since childhood.
 * Delphine from Last Exile has a similar fascination with her brother Dio.
 * And Dio fears her to death, with good reason -- the gal's completely crazy, and not in a good way.
 * Love Hina's most recent segment, the miniseries Love Hina Again, features Keitaro's little step-sister Kanako, who wants to claim him for herself. Throughout her attempted seduction of him she always refers to him as "big brother"...even when half-naked and cuddling up to him.
 * In the manga, it's discussed at length that they are Not Blood Siblings - but Keitaro treats Kanako as if they are. As such, he's remarkably freaked out by Kanako's attempts at seduction.
 * Magikano plays with the trope: The main character's oldest sister has a downright obsessive love for him (one that is definitely not simply sisterly) even to the point where she claims she will marry him and becomes ultra possessive whenever any other girl shows any interest. However he doesn't seem to have any interest in her. The arrival of the protagonist's Magical Girlfriend makes her intensely jealous and always vying for his attention.
 * Despite the show's fanservicey roots, it's never portrayed as actually romantic or sexual though. The manga on the other hand...
 * In Marmalade Boy, Yuu and Miki become step-siblings when their parents marry (with both sets of parents splitting up and marrying each other), and then find themselves growing attracted to each other.
 * Interestingly, the Mangaka (according to her notes on the series) originally planned for them to discover that they were blood siblings and split up for good, eventually hitching up with their unrequited love interests in a Distant Finale. Her producer convinced her that it wouldn't go down well with the fans...
 * In Maze Megaburst Space, not only is the central couple a pair of blood siblings, and not only is the central plot their successful and unrepentant plot to be together, but it goes even beyond that...
 * Onegai Twins has what may or may not be an incestuous Love Triangle, between a boy and two girls who both claim to be his twin sister. To add to the blurring of the line, the girl who turns out to actually be his twin is different between the anime and the novelization. Interestingly, though, the setup of the plot clearly steers away from this: whoever turns out to be the twin must step out.
 * That said, both girls kiss Maiku before it's over, so be ready for some Squick. The possibility of being his sister keeps them from getting really aggressive, but that's all it does; their ambitions are not deterred.
 * Meanwhile, perhaps to provide contrast, there's a minor character (Matagu) who's blatantly attracted to his little sister Haruko.
 * And Haruko doesn't quite reciprocate, but at least clearly knows and doesn't mind. After describing his use of the Hands-On Approach, we get this:


 * The attraction in this series isn't all that unrealistic. The Westermarck Effect isn't in play, since the twins were separated at a very young age (maybe 2 at the latest), and the general principle of genetic attraction makes it unsurprising that the sister would have some feelings upon seeing someone who may (not) be her brother. That the other is a childhood friend makes it all the more probable, since they would have subconscious affection for one another at the outset. That being said, if kissing somehow Squicks you (the convent just called...), there is some of that and some hand-holding/hugging between the would-be sister and the brother. Otherwise, this is an Averted Trope, since, as stated, the twin is not allowed to continue the relationship (which is part of the drama: which girl has to give up her romantic affections, and which girl gets to be by his side albeit as a sister, not a lover).
 * Maiku does have a hard time not having sex with either of them in the Beach Episode (complete with imagining them naked, though admitedly chibified) and has to resort to leaving the room to contain his libido. Knowing one is definitely his sister doesn't stop him from wanting them BOTH.
 * Ore no Imouto ga Konna ni Kawaii Wake ga Nai! - Whether or not siblings Kirino and Kyosuke do or don't have a sexual attraction/hidden desire to each other is the Elephant in the Living Room of the series.
 * In Revolutionary Girl Utena, not only does Touga's sister Nanami harbor an intense crush on her older brother, but she also has a near-insane jealousy of anyone or anything that might attract more of his attention and love than she does. There is also the strange love-hate relationship between Kozue Kaoru and her twin brother Miki, best displayed in the bizarre bathtub-and-straight-razor scene from the Utena movie. Most important to the plot, though, is.
 * In the first example, a few of the last episodes of the series deconstructs Nanami's infatuation with her brother by introducing the possibility that they are not siblings and explores Nanami's emotional confusion resulting from that distancing.
 * Ali and En in the anime-only "Makaiju" ("Doom Tree") arc of Sailor Moon. This is explainable to an extent, however: not only are they the only surviving members of their species, but they are "children" of a tree, which used what remained of its powers to "grow" them after the rest of the species was destroyed in warfare; thus making them "siblings" in roughly the same sense as Adam and Eve.
 * Lampshaded once by Makoto, when "Natsumi" bitches "Seijuurou" out for letting Mako offer him a part of her lunch. She's squicked and says something by the lines of "Wow... these siblings! So weird!"
 * DiC, perhaps in a result of bowdlerize, had Crimson Rubeus refer to his four main female minions as sisters. He may have referred to their name, Phantom Sisters, but it calls into suspect when you realize most of them are attracted to him.
 * Saint Beast: Definitely played with in Kira and Maya, particularly in the official art.
 * Tiriel and Sorath in Shakugan no Shana have an incestuous relationship, though in this case it's portrayed in a creepy light. What they are muddles the water, but only somewhat. Shana seems to take more offense at the French kissing than anything else.
 * Alti in Simoun is obsessed with her sister Kaimu, and tries to prod her into choosing to be female so that Alti can become male and "protect" her.
 * They also have sex once during the course of the show (long story) and in the Distant Finale they are living together.
 * Sister Princess and its "sequel" series, Sister Princess Repure, both have incestuous subtexts, but the subtext surfaces clearly in Repure: in the very first episode, Karen recounts how she decided that she would be her brother's bride, despite society's disapproval of such a thing. In the original series it is less visible, although still present—one sister (Chikage) was, Sakuya openly flirts with him (Rin Rin and Mamoru are more subtle hiding their flirting under the disguise of admiration for their Brother), and all twelve spend one episode making mock wedding dresses so they can play at being his "bride".
 * In Soul Taker, Runa wanted to marry her twin brother Kyousuke, who declined the honor.
 * Ren and Mihato in They Are My Noble Masters have a mutual brocon-siscon relationship, and are quite supportive of each other. It's almost sweet if one is willing to look past the sibling thing. Then again, this is a show that's filled to the brim with fetishes. They do have a route together in the original h-game.
 * In the same series, Shinra is very open about her sexual attraction towards Miyu, her younger sister. Worse, she sexually assaults her on numerous occasions, which is played entirely for laughs. That Miyu seems to be very ambiguous about this and that the youngest sister is actually jealous for being left out just adds to the Squick-factor. Fetishes, indeed.
 * Nasu Kinoko loves this trope:
 * In Tsukihime, Shiki's sister has a very possessive crush on him. Parodied in numerous doujinshis and official omakes, including one where Ciel points out the hopelessness of the crush. Shiki's feelings are purely platonic. And a large part sheer terror—Akiha is tsuntsundere at best and Yandere at worst. Of course, Akiha does have her own path in the Visual Novel.
 * Though they never did anything incestuous,  hints many times that he has romantic interest in his sister
 * On that note, Azaka from Kara no Kyoukai, who can be considered prototype of Akiha above, also loves her brother deeply, to point where it gets in the way of her becoming friends with the series heroine Ryogi Shiki. Her love may not be the same in nature as Akiha's but since she and her brother were used as a strong basis for Akiha and Shiki, it is likely that the "love for my brother" was carried over as well.
 * While we're on the note of Nasuverse, in Fate/Stay Night, has quite a bit of affection which could be considered romantic for
 * Which is alive and well in Fate/kaleid liner Prisma Illya.
 * The Spiral manga has a variation: Ayumu was in love with his sister-in-law even before his brother married her, and lived with her after he disappeared. Also,.
 * All but expressly stated in Edens Bowy between tragic siblings Wietoo and Hairra. Initially averted when Hairra actually tried to pair her older brother Wietoo together with her best friend Fennis in an effort to repress her own incestuous feelings, but it failed anyway due to irreconcilable differences of ideology between Wietoo and Fennis, who also noticed Hairra's disturbingly excessive attachment to her sibling. Eventually the siblings get together when Hairra decides to acknowledge her feelings upon realizing that no one would love her brother as much as she did (which led to a falling-out with Fennis) and Wietoo also realizing that only Hairra would ever accept all of him, including his controversial views on the creation of sentient A.I. Hairra is soon killed tragically sometime afterwards when Wietoo's first android goes berzerk, and she is reborn as his personal gynoid weapon/bodyguard. Later, when they are both killed at the series end, they are reborn together as sentient programs together roaming forever their world's version of the internet.
 * Aono in Sola is obessed with her (younger, for a change) brother Yorito.
 * It is heavily implied in Narutaru that the bully Aki Honda and her older brother Yasuhito have a ... rather intense relationship.
 * It's downright spelled in the manga.
 * Said scene is censored in many countries in the world (even the japanese version got censored retroactively) and spelled the end of the series' publication in many others.
 * Renhou and his sister Miiru in Fushigi Yuugi.
 * The first episode of Voltage Fighter Gowcaizer, the Villains Of The Week were an incestuous set of twins (who were empowered by the Big Bad Evil Guy to save the dying sister) who merged into a gestalt monster "powered by love".
 * Infinite Ryvius spoiler:
 * Kanan is Hakkai's older sister in the Saiyuki manga, although this was edited out of the anime version, and, as they had been Separated at Birth or very close to it, they weren't originally aware of it. A tie-in novel also suggested that they might be twins as well, which was approved by Word of God.
 * Miyuki Takamachi in Triangle Heart 3 ～sweet songs forever～ is actually Kyoya's cousin, but adopted as his sister. In the game she's an option, though in Canon he chooses to be with his Patient Childhood Love Interest, Shinobu. Yes, this shows up in early episodes Magical Girl Lyrical Nanoha; watch as Kyoya states he's going to visit Shinobu. For one second she shows jealousy, and then it's never mentioned again.
 * She seemed more annoyed at his using accompanying Nanoha to visit Suzuka as an excuse to see Shinobu, given that he doesn't seem completely open about his relationship (In A's episode 9, she teases him about being able to work with Shinobu for Christmas with a cute smile on her face). Interestingly enough, Miyuki calls him "Kyou-chan" (like she did in Triangle Heart) instead of "Onii-chan", like Nanoha does, which may indicate that they're Not Blood Siblings.
 * In Clannad, Tomoya's wild imagination causes him to imagine the Sunohara siblings as this when he misinterprets one of Mei's lines.
 * In True Tears what starts as a case of Big Brother Instinct evolves into borderline incest when we learn that Jun has romantic feelings toward Noe, his younger sister. This trope is also averted.
 * from Shugo Chara loves the resident Bishonen catboy of the series, Tsukiyomi Ikuto. The thing is,, which does explain why Ikuto is so cold towards her advances—in fact,.
 * The secret of the Kuhouin family in Kure-nai is that.
 * In Ghost Hound, the main character, Tarou, has a slight obsession with his sister which leads to him accusing the girl he likes of being his sister reincarnated as an explanation for why he thinks about her all the time.
 * In D.Gray-man, Komui's attitude toward his sister Lenalee straddles the line between Big Brother Instinct and this trope; even the other characters find it a little creepy and frequently remark on his obsession.
 * Candy Boy's main theme is the yuri subtext between (fraternal) twin sisters. The lyrics in the recap video appended to the first episode proclaim that "this may be the best pairing in the history of the world". Ahem.
 * Vampire Knight:
 * Adopted? No, they're full-blown siblings.
 * No, he was adopted, it is fully explained later in the manga.
 * Berserk subverts this somewhat, since
 * Minato and Juunichi's relationship in Akane-Iro ni Somaru Saka is seen as this by everyone despite the siblings' insistence that it's not. It turns out everyone else was spot on, because when the show ends, Minato is the one who ends up winning.
 * Interestingly enough, the level of incest between Minato and Juunichi changes depending on the version of the story. They're fully blood-related in the original PC game, but Minato is adopted in the PlayStation 2 version and possibly in the anime as well.
 * In Mahou Shounen Majorian, Mari falls in love with the magical girl form of her brother, Masaru—which makes it kind of hard to classify.
 * Axis Powers Hetalia has both the traditional brother/sister version and a Ho Yay one. On a hand, the Yandere Belarus would love to marry her older brother Russia (also a Yandere), which freaks him out no end. On the other, the Annoying Younger Sibling South Korea isn't much more successful in getting his older brother China (and sometimes his other older brother, Japan), to acknowledge his more-than-brotherly affection. Both cases are played for laughs.
 * There's also America and England, subject to quite a bit of Ship Tease. America was adopted by England as his brother, though he has since announced that he is "not [England's] little brother anymore".
 * At one point in the Ah! My Goddess manga, a botched love potion fed to Keiichi causes any female who looks into his eyes to become passionately infatuated with him—starting with his sister Megumi. She says, "Our love can transcend these foolish bonds of blood!" His horrified reaction: "Oh no it can't!" Fortunately, neutralizing the potion wipes her memory of the incident.
 * As you can easily guess, there are Hentai dōjinshi expanding on this incident.
 * The anime-remade episode has this too, and is more outrageous, where Megumi goes to the length of clinging onto Keiichi and fighting over him with Skuld, Urd and Peorth who also fell victim to the effect of the potion.
 * That clinginess and fighting the others is also in the manga, but Peorth doesn't get caught by it.
 * In Minami-ke, Chiaki and Kana's adoration of Haruka many times looks extreme, the fact that they talk about her possessively and will scrutinize any potential love interest says something.
 * in Kare Kano, Kazuma and Tsubasa simutanously get crushes on their other as their parents get married. Cue Squick from parents, Wangst from Kazuma which make him run away from home, which makes poor Tsubasa down the mental road before it gets better
 * Somethinged in Fresh Pretty Cure. Miki's brother Kazuki lives with her father (her parents are separated, presumably divorced) and uses his name. She hasn't told her best friends they they're related, and in the first episode she refers to their upcoming outing as a date. The second episode focuses on one of their dates; it also features The Reveal that they're related, but you'd be forgiven for missing this detail. Eventually it's revealed that, when her friends assumed Kazuki was Miki's boyfriend, Miki went out of her way not to correct them because she thought it was cute.
 * Vampire Game: It's a big, feuding Royally Screwed-Up family, and brother-sister incest is the least of their problems—that couple looks downright normal in comparison, Love Makes You Crazy moments aside.
 * Particularly since it includes a case of brother/BROTHER incest... sort of.
 * Happy World: The explanation Takeshi uses to explain Elle's connection to him is that she's his step-sister. Cut to Takeshi exclaiming loudly to her in a classroom "We should make a baby." And they actually go halfway through the act before realising that they're not emotionally ready for it.
 * As it turns out, their relationship to eachother
 * Their child, Prayer, is eventually born... but not through normal means. Takeshi and Elle
 * In Shoujo Sect, one of the early hentai scenes is between sisters. Momoko gets upset that she (unwittingly) and Shinobu (less so) helped set this up. The amusing thing is that if she hadn't said so, we wouldn't have known they were sisters, what with all the Onee-Sama-ing that goes on at all-girl schools. Their sharing a last name is also kind of a clue, though admittedly that detail might be easy to miss.
 * Ninin ga Shinobuden has Sasuke imagining that he's the object of an Unwanted Harem. He disturbingly imagines that Shinobu is his sister.
 * Oniichan Control has the brother who fled from his younger sister because he's developed inappropriate feelings for her. Unfortunately, his younger sister is not only fully aware of these feelings, but returns them in a big way. And she's a first-rate manipulator beneath her cutesy facade, managing to track him down, get admission to the same college he goes to, and worm her way into becoming his roommate. This goes so far that she's willing to stab a girl she thought was interested in her brother. The entire series is about the brother trying to avoid this trope while the sister tries to invoke it.
 * Two examples of this, running in both directions, are present in Hatsukoi Limited. Ayumi's brother, Yuuji, is a definite siscon, and Koyoi Bessho is defined by her brother complex. Of course, they are but one small part of the Love Dodecahedron that permeates the series.
 * In the spinoff of Genshiken, Kujibiki Unbalance has the main character's sister pursuing him endlessly, even going so far as to.
 * An example also occurs in Yuu Watase's pre-Fushigi Yuugi manga, Shishunki Miman Okotowari. Asuka Higuchi falls for her half-brother Manato Sudou early on in the story, and he eventually comes to reciprocate.
 * In Shinkon Gattai Godannar, English pilot Knight Valentine will flirt with any female in sight, much to the consternation of Ellis, his sister and partner, who thinks he doesn't notice her. But if
 * This issue is addressed in a second season episode of Hell Girl. The incestual love in this case is one-sided, and the offending sibling is, of course, sent to hell. The episode ends on a lighter note; the aforementioned sibling is not tortured on the ferry (unlike sinners who have done worse), and there is the knowledge that the brother and sister will eventually be reunited as per the terms of the curse.
 * The Manga and Anime of Kiss×Sis is Onegai Twins on steroids The basic plot is this. Keita is a 14 year old junior high school student studying for his high school entrance exams. He has two older stepsisters in high school Riko and Ako. One day his sisters decide to bring him lunch while they have free time from school and end up confessing their love to him in front of his class. To make matters worse, his father and stepmother are completely OK with this—in fact his mother is taking bets among the neighborhood housewives on which girl he gets first!
 * This troper only saw the first episode of Queen's Blade, but Elina seemed quite obsessed with her sister Reina, showing flat out disappointment that she couldn't spend the night in her room.
 * It's canon. She DOES want to sleep with her sister, and Reina seems to be the only one who doesn't seem to notice Elina's blatant lesbian crush on her. To be fair, no one else (not even Claudette, their older sister) comments on it, at least in the anime version.
 * Claudette gains a similar desire for Reina in one of the Rurou no Senshi omakes.
 * The original OAV series of Tenchi Muyo! is filled with incestual attractions—the whole mess basically got started when Ayeka fell in love with and was engaged to marry her elder half-brother Katsuhito/Yosho. See Incest Is Relative for full details.
 * in Loveless towards Ritsuka.
 * Silvia in Genesis of Aquarion has a pretty obvious attraction to her older brother Sirius, becoming incredibly jealous of even the slightest hint of romantic interest in other women. It seems her insistent belief that he is the reincarnated lover of the woman she is the reincarnation of has a lot to do with this.
 * In Lady Georgie!, the Plucky Girl Georgie is romantically pursued by her two adoptive brothers, Abel and Arthur. Since the three were raised together and Georgie herself didn't know she was adopted for many years... well, yeah.
 * This is a catalyst for one of the storylines in Mononoke.
 * In Urusei Yatsura, the Mizunokoji siblings have a one-sided version of this going on... more or less. According to their screwed up traditions, youngest daughter Asuka was raised in total isolation from the opposite sex, and with the terrible job her maids did in regards explaining the other sex (something worsened by her fact her first encounter with a guy was Ataru Moroboshi), she's terrified of men... except for "Big Brothers", whom her maids made out as a special, dependable, trustworthy exception to men in general. Between her phobia and her naive ignorance, she not only has a crush on her ilder brother Tobimaro, but is constantly trying to perform deeds with him that are only appropriate between lovers. Tobimaro, meanwhile, is perfectly aware of their relationship and that the things she tries are not appropriate, thus he freaks out when the poor girl comes on him. The fact that their crazy mother blames Asuka's actions on him, despite the fact she was the one who arranged for Asuka to be raised the way she was, only makes things more galling for him. The fact Asuka also has Super Strength and is thus prone to crushing his bones whenever she gets frightened or romantic does not help.
 * 15-year-old Sakurako Saiki from Sakura Gari is a scary Yandere who is incredibly possessive of her older brother, the main character Souma, . For further subversion,  . And even more subverted:
 * The second episode of the Hentai anthology series Cool Devices focuses on a wealthy man lusting after his sister; and in the end, they... =well, you know.
 * Iina from Kokoro Library appears to have quite a thing for her sister Kokoro. She tries to steal kisses from her and gets quite upset when Kokoro decides to spend time in the bath with her other sister, Aruto, instead of her. Kokoro clearly loves Iina a lot too, but in a sisterly fashion.
 * Basically the plot of Aki Sora.
 * In Freezing, Satellizer was abused by her half brother. He molested her as well, and though it is unknown how far he went with it, it was enough to scar Satellizer to the point that she could no longer stand being touched by anybody.
 * And, for some irony, the one guy who's the exception, the one guy who can touch her because he treats her with dignity and compassion? He was attracted to her initially due to her resemblance to his big sister, and
 * Kurei and Kurenai from Flame of Recca, anyone? Mori Kouran was already the adopted father of Kurei, then he was revealed to also have adopted Kurenai when she was . Let's not forget that both Kurei and Kurenai were in love each each other and actually a couple in canon. Sure, they didn't share the same blood, but they both had the same adoptive father, so therefore legally it's incest.
 * This is a plot point in Kagihime Monogatari Eikyuu Alice Rondo. The main characters are a boy named Aruto, his love interest Arisu, and his little sister with a very obvious crush on him, Kiraha. It is revealed later that
 * Combined with Parental Incest in Boys Empire.
 * Shinogu and Hatsumi from Hot Gimmick are Not Blood Siblings. Shinogu is in love with Hatsumi but, in an effort to not burden her with his feelings, he tries to put distance between them. Hatsumi actually offers herself sexually to Shinogu at one point but he turns her down. And in the Hot Gimmick S novel, she actually leaves her abusive boyfriend Ryoki for Shinogu.
 * In Durarara!!, . Izaya finds it a bit disgraceful.
 * Izaya's younger twin sisters Kururi and Mairu are also Twincestuously close to each other. In the anime it comes rather out of left field when they make their only proper appearance in the series in a DVD-only episode, and suddenly make out without any kind of foreshadowing, only for it to be never mentioned again.
 * Likewise, the novel adaptation of Baccano! says that Graham Specter's first love was his sister. No information has been given beyond that so far.
 * In Gankutsuou Andrea actually tries to marry and rape his half-sister Eugenie. Though only to deliberately humiliate her and her family.
 * Sakura Hime Kaden has this. Proof here.
 * The brother-sister incest relationship is the central plot of the manga Tsumi ni Nureta Futari.
 * Ryo from Final Approach is quite obsessive over his little sister Akane and she's generally reciprocative. It's generally played for laughs as nothing more than an amusingly intense sister/brother complex, but it is worth noting that Akane insisted on taking part in the contest with the other girls to see who got to play the role of Ryo's bride.
 * When Akane is sick Ryo rushes home to take care of her. It's at this point the other girls realize they're not competing with each other but with Akane.
 * In the anime of Samurai Deeper Kyo, Big Bad Nobunaga Oda and his right-hand henchwench Shatora are an incestuous brother-sister pair who desire who turn the "boring world" of 19th century-Japan into a literal "hell of battles" so they can openly be together in the chaotic new world. They reveal that their Start of Darkness was because society tried to force them apart by making their relationship taboo in the first place.
 * SDK is not set in nineteenth-century Japan! Rurouni Kenshin is set in 1878. SDK is set centuries earlier, although its Anachronism Stew does not always make this apparent.
 * In The Kindaichi Case Files, a man masquerading as a serial killer is on a Roaring Rampage of Revenge for his dead lover...it's revealed after he is Driven to Suicide that said lover was his sister. (And the lake where the murders take place is rumored to have been the suicide spot of another pair of sibling lovers.)
 * Lisa Fukuyama in Girls Bravo. In the 1st episode of the second season, Yukinari has temporarily traded bodies with her older brother but she's still planning on sleeping with him.
 * Pretty much the fundamental appeal of Yosuga no Sora combining with Twincest.
 * In Corsair, Jean-Hughes saves his seven year old brother Canale from being raped, but he can't stop imagining himself doing the exact same thing to him. This leads to him pinning the guilt and blame on Canale and loathing him even more.
 * Cain Hargreaves, the lead of the Count Cain manga and its sequel series Godchild, has this as part of his origin story. Turns out part of why he has the family curse so bad/ slash why his parents always acted so weird with him/why he has sort of golden eyes, is that his mother isn't his mother. His father's crazy sister Augusta is. When he finds out and goes to see her in her asylum, she jumps to her death in front of him.
 * For some reason, Kaori Yuki decided to reveal in the end that Magnificent Bastard Alexis was actually manipulated by his much more evil sister Augusta because...she was just that evil, apparently. Yeah, evil enough to seduce her brother into impregnating her and then spend the next twelve years catatonic in an asylum before killing herself just to traumatize the kid. According to her ghost, at least.
 * Junai Labyrinth is all about Umi, who has incestuous feelings for her older brother Haruto.
 * Flowers of Evil: the central theme is the sister's obsession with her brother.
 * Lola and Layla from Venus Versus Virus have implications of a Sister-Sister version of this. Lola seems to not recirpocate her obsessed twin sisters feelings though.
 * In One Thousand and One Nights, Dunya is infatuated with her older brother Sehara. She actually demands that he kiss at one point (which he does).
 * Somewhat referenced to in Higurashi no Naku Koro ni. Mion Sonozaki mentioned in the sound novels that she'd marry Shion if she was a boy, not mentioning if they weren't related.
 * The official art including the sisters does NOT help.
 * Mawaru Penguindrum's first episode has Kanba Takakura kissing his younger sister Himari after she's resurrected and while she's sleeping. It hasn't been referred to later, though. Let's give it time.
 * It's given a rather philosophical twist in this series; Kanba's Internal Monologue in the scene revolves around defying fate and the animalistic survival strategy to determine one's free will. Basically, doing something that your very biology abhors is used as a sign for freedom of choice.
 * In the Penguindrum novel, the scene where a posssessed Himari pulls something out of Kanba's chest is a little more suggestive than in the anime version. Not to mention, in the anime the kiss scene went into fade to black when Kanba's lips were milimeters away from Himari's. In the novel? It's described quite in detail.
 * Taken further in episode 12, where  Though there may be a twist here,   It happens again in episode 17, when
 * Aaaand then...
 * Then finally reintroduced in the form of Twincest when
 * Oniisama e... has  as one of the driving forces of the plot.
 * Averted in Baka to Test to Shoukanjuu because while Akira really wants to move her relationship with her younger brother to the next level, the normally super-horny Akihisa surprisingly expressly considers incest to be disturbingly immoral and constantly resists the nonstop attempts at seduction of his older sister.
 * To LOVE-Ru seems to heading this way, if Momo gets her way. Played for laughs when Mikan trying to resist the effects of Celine'spollen.
 * In Yuki Suegutsu's infamous Eden no Hana manga, the protegonist, Midori, was put in foster care and then was raped by her adoptive brother.
 * MM! main character Taro is actively pursued by his older sister AND mother. When he gets amnesia for an episode both try to pretend being his pregnant lover.