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Light Novel / Oni Ai

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After six years of living apart due to their parents' death, Himenokouji Akito decides to have his younger twin sister, Akiko, living together with him as a family. The problem is, Akiko is deeply in love with him and unashamed of it, actually displaying her incestuous affection beyond common sense instead.

The wackiness of Akito's life actually had already been quite severe even before his sister's arrival. As a caretaker of his school's student council's dorm house, he had been living together in said house with the three members of student council who happen to be attractive yet very... unique girls: Arashi Nikaidou, Anastasia Nasuhara, and Haruomi Ginbei Sawatari. Another girl, Akito's stepsibling Arisa Takanomiya, arrives later in the anime as a housekeeper. They are all craving for Akito's affection.


Needless to say, Akiko's battle to make her [im]pure love come true begins. Basically, think Seitokai Yakuindomo if the girls were more sexually aggressive. Really aggressive.

This light novel series, whose Overly Long Title translates to "As Long As There's Love, It Doesn't Matter If He's My Brother, Right?" and which is often shortened to OniAi, was made into an anime by SILVER LINK. studio and aired during the 2012 fall season. The anime can be viewed legally online at the Funimation site. This is also FUNimation's first sub-only release as means of experimenting sub-only releases for more niche titles (although as usual, they encourage people to support legal releases and streams if they want their favorite anime to dubbed).


This light novel/anime series makes use of these following tropes:

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  • Absolute Cleavage: Arashi at the dorm.
  • Alliterative Family: Akito and Akiko.
  • Animal Battle Aura: Akiko (tanuki) vs Arisa (cute rabbit) (ep 7).
  • Babies Ever After: This happens at the end of episode 11. It is even implied that Akito is the father of Akiko's best friends' unborn children. It is All Just a Dream Kaoruku is having.
  • Big Brother Attraction: Akiko makes it very clear how much she likes Akito. While, Akito tries his hardest to remain indifferent to his sister's affection.
  • Bokukko: Ginbei.
  • Bread, Eggs, Milk, Squick: When Akito falls ill, Arisa brings in a massive selection of foods as well as a few non-food items to help him get well. She lists out the non-food items: "... pickled plum to crush on your forehead, a sake-soaked hot cloth, a fried leek to insert rectally, some garlic..."
  • But Not Too Foreign: Anastasia.
  • Clingy Jealous Girl: All of the girls exhibit this to some degree, but Akiko really cranks it Up to Eleven with her obsession. Aside from constantly trying to get into incenstual relationship with her brother, she can also remember how long ago she's spent important times with him, down to the minute. Which gets into very awkward territory when it happened years ago.
  • Cringe Comedy: A more benign than usual example, but still...
  • Cold Opening: As with most other animes, though several of the cold openings can last so long that, by the time the opening credits come on, it would already have been as far as eleven minutes into the actual episode.
    • Ep 7: By the time the opening ends, there's only 16 seconds before the mid-episode eyecatch.
  • Cuteness Proximity:
    • Anastasia towards Arisa. She even dissuades the latter from getting a bikini swimsuit and settling for a one-piece so as to maintain her youthful look, under the guise of waiting until she gets older to start looking more woman-like to Akito then.
    • Ginbei towards a stray kitten at the beginning of episode 9. Aside from making cutesy "nyaa/meow" noises, she even sports a Cat Smile from time to time while spending time with the kitty.
  • A Day in the Limelight: Each girl gets at least one episode that focuses heavily on their solo interaction with Akito.
  • Deadpan Snarker: Anastasia. Her monotone voice and lack of facial expression often makes anything she says sound very sarcastic, even if she's serious about the subject.
  • Does This Remind You of Anything?: The whole opening can give just about anyone certain ideas.

  • Girls Love Stuffed Animals: Anastasia again.
  • Go Mad from the Revelation: Akiko flips out when Anastasia "confesses" to Akito.
  • Going Commando:
    • A brief segment of episode 3 involving the laundry concludes with everybody wondering why Arashi's underwear is nowhere to be found. Arashi clears up the confusion by explaining that she never wears them around the house, followed by a sudden gust of wind that provides confirmation.
    • Anastasia spends the entirety of episode 11 with no panties under her usual miniskirt, resulting in repeated Hilarity. Special mention goes to the exquisite detail with which she describes the circumstances that led to her misplacing her underwear, chews herself out for her carelessness in doing so, and finally resigns herself to going without them.
  • Informed Attribute: Probably Played for Laughs. The so-called love between siblings that Akiko talks about is so fucking one-sided that you may as well call her a delusional family-friendly (for a given value of family-friendly) yandere.
    • May not exactly one-sided. Both Ginbei and Anastasia concluded that Akito is a siscon. (While he himself denied it, though it was most likely to mess with him)
  • Innocent Innuendo: Ubiquitous.
  • Irony: Akito writes Brother–Sister Incest stories.
  • Kind Hearted Cat Lover: Ginbei.
  • Laser-Guided Amnesia: Played for Laughs as an accidental hard hit to the head erases the events of Arashi Going Commando revelation from Akito's memory.
  • Letting the Air Out of the Band: Multiple times per episode.
  • Lovable Sex Maniac: Arashi wants to make this very clear. To everyone. Emphasis on very. Anastasia and Akiko also tend to be uncomfortably-frank and honest about expressing their sexuality and states of arousal, much to the chagrin of Akito and the horror of innocent little Arisa-chan.

  • Marry Them All: This happens at the end of episode 11. It's All Just a Dream Kaoruku is having.
  • Modesty Towel: Frequently, both in front of Akito (for the sake of teasing him) and in private (for the sake of teasing the viewers).
  • Mrs. Robinson: Akito's editor tries to (clumsily) seduce him after finding out about Akiko and fearing that his published Brother–Sister Incest stories are an expression of real lust toward his sister.
  • Mundane Utility: Anastasia uses her father's Multibillion dollar global company to make some simple things for herself. Usually lampshaded by Akito.
  • Nice Girl: Arashi, despite being a Depraved Bisexual, is actually pretty nice and far from a Jerkass.
  • Nice Guy: Akito, but it's later subverted when it becomes clear how much he actually enjoys seeing Akiko become flustered and anxious.
  • Not Distracted by the Sexy: Akito towards his sister, which is understandable considering they're siblings. She gets mad at him when he tells her to take a bath first, but doesn't go in to peep on her. She then storms to his room in her towel to demand why he hasn't.
  • Odd Name Out: Ginbei, while all the other members of the dorm/student council start with an .
  • Panty Shot: Not only are there quite a few of them onscreen, but it's also a common discussion theme between the characters, with a girl either asking Akito to look up her skirt, or accusing him of doing so. Sometimes in the same sentence.
    • Anastasia tends to complain that Akito is looking up her skirt (even when she's wearing shorts, like in ep 4), while Akiko complains that he doesn't.
  • Patient Childhood Love Interest: Ginbei
  • Perpetual Smiler: Downplayed, yes, but Akiko has perfectly good reasons for smile to give way to other expressions when it's a matter of her and her brother's happy future together.
  • The Pirates Who Don't Do Anything: The five main characters are the school's student council. You'd be forgiven if you forgot, since they never do anything remotely student-councily. The only times we ever see them vote on something during the anime is usually discussing something about what they will do when they get back to the dorm.
  • Playing Gertrude: Akiko's voice-actress (14 at the time of recording) is actually two years younger than her 16 year old character; a rare reversal of the usual Dawson Casting practices of the current anime industry.
  • Proper Tights with a Skirt: Akiko and Arashi
  • Rapunzel Hair: Arashi
  • The Reveal: At the end of Volume 1/Episode 12, Akito makes it clear for the audience that he is not in fact blood-related to Akiko. In a later volume he reveals that he found out at a young age that he was adopted—his parents asking him to keep this secret from Akiko, the rest of the family and all others.
  • Refuge in Audacity: Even the opening credits is very guilty of this.
  • Samus Is a Girl: Akito to Ginbei in Ginbei's flashback.
  • Shameless Fanservice Girl: All girls except Ginbei may count.
  • Shout-Out: Arashi gives us three, her Signature Laugh is very similar to another student council president.
  • Sick Episode: Akito in episode 10.
  • Signature Laugh: Akiko's "Guhehehe~," and Arashi's "KA-ka-ka."
  • The Simple Gesture Wins: When Akito becomes ill, the girls he dorms with decide to take turns nursing him, with each of them competing to see who does a better job. They try feeding him, warming him with their bodies, talking with him, and other various methods. The final girl, Arashi, simply walks into his room, exchanges the warm towel on his forehead for a fresh cold one and leaves. The next day, when the girls demand to know whose methods worked best, Akito says it was Arashi, to the horror of the other girls. note 
  • Student Council President: Arashi
  • Sugar-and-Ice Personality: Anastasia.
  • Suspiciously Specific Denial: Those aren't Anastasia's stuffed animals. That's definitely not one she's treasured for as long as she can remember. She certainly never gave each one a name and talked to them every night before bed.

  • Take a Third Option: In ep 7, when Akiko and Arisa demand that Akito choose between them, he (predictably) answers "I love you both... as my little sisters." It works: They stop fighting.
  • There Are No Therapists: Probably has something to do with the lack of adults with the exception of Kaoruko and some extras, but Akiko needs one. Fast. She probably managed to avoid one because the adults around her before thought that she was only feeling the absence of her brother, but she's so batshit obsessed about him that you may ask how she was living without him all of those years.
  • Title Drop: At the end of the first and last episodes.
  • Token Mini-Moe: Alisa. Kyu!
  • Tomboyish Ponytail: Arashi.
  • Troll: Anastasia again.
    • In later episodes, it seems Akito also enjoys teasing Akiko.
  • Unwanted Harem: Akito has four of them, including his little sisterand some more little sisters. Taken so far past Eleven that the meter broke.
    • In Ginbei's flashback, it is revealed that she sent a diverse group of girls to Akito to prevent him from meeting her.
  • Vapor Wear: Arashi.
  • What You Are in the Dark:
    • When the girls were taking care of Akito, Arashi had him completely at her mercy. What does she do with this chance? Simply changes his warm towel with a fresh cold one and leaves the room.
    • Arashi wins the bet with the girls, the prize being that she gets to spend all day with him alone in the dorms without any of the girls allowed to interfere. Akito, as well as the other girls, fearing the worse. It turns out she spends the day with him dressed up as a noble woman and they spend the day doing flower arrangements and drinking tea. At the end of the day she does tell him to watch out if she gets this option again.
  • Why Did It Have To Be Ghosts: All of the girls are afraid of ghosts.
  • Yamato Nadeshiko: Ginbei and Arisa. Arashi pulls one off when Akito has to visit her room in Episode 10.
  • Yandere: Akiko, to the level that she is an Flat Character whose only trait is being "in love" with her brother, that it borders obsession. Thankfully she never goes Ax-Crazy. Or would be lamentably?

Alternative Title(s): Oniichan Dakedo Ai, Onii Chan Dakedo Ai Sae Areba Kankeinai Yo Ne