OniAi is short for Onii-chan Dakedo Ai Sae Areba Kaneki Nao yo ne, which translates as “As Long As There's Love, It Doesn't Matter If He is My Brother, Right?” That should be taken both literally and as a firm indication of which direction the content goes in this 12-episode 2012 series, as the most common focus of attention is Akiko's earnest efforts to make Akito her lover and future husband despite his usually-polite but firm refusals. And yes, that does quite clearly include wanting to bone him, a point she is emphatic about on many occasions; she even proudly declares that she is a “brocon” (short for “brother complex”) and wears a variety of T-shirts with messages to that effect. While that kind of content may drive away some potential viewers, there is a better and simpler reason to avoid this one: even by the low standards of harem series, it isn't very good.

Given the popularity of quasi-incest themes in otaku-focused series over the past few years, the intent here is clear: build a full-blown, unabashed harem series centered on a female character who is so proudly incestuous that she believes that her blood relation to her brother should give her an inherent advantage. Keep the male lead so steadfastly standoffish that he comes across as a total prude and populate the harem around her with combinations of, and minor variations on, common harem archetypes: the aggressively bisexual girl, the childhood friend who laments about looking too boyish, and the rich girl who constantly twists everything into a fantasy scene or sexual reference. (Her name is Anastasia, so her favorite ongoing gag is to try to get Akito to call her “Ana” and play it off as him making a crude reference to one of her “holes,” since “ana” means “hole” in Japanese. Yes, this is how creative the series gets.) Since lolicon is also popular among Japanese otaku, one naturally has to be thrown in for good measure. To make sure all tastes are covered, why not toss in an adult woman, too? All sorts of hijinks naturally go on as the girls battle over Akito and try to come on to him.

All of this is pretty standard harem fare, and the series might get away with it just fine if not for two fatal flaws. The biggest and most lethal is that the writing fails to make the girls at all interesting. The core of the harem is intact almost from the beginning, with the three secondary girls all suddenly appearing with no real explanation beyond the fact that they, along with Akiko, compose the school's Student Council. Why Akiko is so passionately devoted to her brother is never explained, nor is why the President is so into Akito (beyond the fact that she seems to lust after anything that moves, whether male or female), the romantic interest of the childhood character is more or less assumed without any elaboration, and rich girl Anastasia is implied to be interested in Akito simply because Akiko, who's she known and been fascinated by for several years, is infatuated with him. (And even this much is not explained until late in the series.) Their personalities, when they show any at all, are often more obnoxious than entertaining, and not until the last three episodes is any real effort made to develop them. The introduction of the loli girl does not improve the status quo, as she is defined mostly by a supposedly cute sound she makes when distressed – and really, why would a 12 year old genius who's already graduated from college want to be something as utterly mundane as a dorm manager, anyway? She never shows any degree of exceptional intelligence or wit, so one must assume that her genius status is simply a cheap way to explain why she is there and not in school. The book editor lady is a little better and the only character who is consistently at least mildly entertaining; her fever dream late in the series imagining Akito having fathered children by all of the female characters in the series (apparently at the same time!) is easily the series' funniest gag.

The other fatal flaw is that the writing too often fails to be funny. Too many of the attempts at humor either outright bomb or are drowned amidst oceans of obnoxious behavior, and others that are funny once then get beaten to death over the course of the series. The running joke about how Akito is secretly the author of brother-sister incest stories that his sister adores, despite adamantly insisting on not loving his sister “that way,” even puts an uneasy light on their relationship. The fan service is not nearly sexy enough, or prevalent enough, to offset this, either. As a result, the first roughly two-thirds of the series is sheer drudgery to sit through, with only an occasional bright spot where a joke or gimmick actually works. The writing does improve in a small but significant way in the last third as the series starts exploring its characters more and comes up with some more genuinely humorous scenes and routines, so those who successfully slog through the early dreck will be rewarded in at least a small way for their perseverance. However, even then it is marred by some awkwardly-placed episode breaks and failing to come to any kind of proper ending; instead it drops a couple of big reveals at the very end and then claims that they will be explained some other time. Director Keiichiro Kawaguchi has helmed genuinely entertaining series before (Minami-ke, Hayate the Combat Butler, Sket Dance), so one has to wonder what happened here.

The lively opener for the series strongly suggests that this will not only be a fan service-laden series but also a particularly saucy one, as among other things it has Akiko seeming to give Akito a lap dance and briefly implies that Anastasia is giving Akito a blow job. However, most of the series ends up being surprisingly tame beyond Anastasia's dialogue. Nudity is present in fleeting glimpses but panty shots and other common fan service staples are less pronounced than one might expect. (The one amusing twist here is one late scene where the two least-developed girls try to feel each other up, with humorously awkward results.) Only in the six short omake does the fan service go full-bore, and the 12 year old is a full participant; avoid the last one if you normally find loli fan service too edgy for your tastes.

Outside of the barely-animated omake the SILVER LINK team produces a solid production effort, include sharp backgrounds, good animation, and rich, textured use of color. Character designs are distinct but not overwhelmingly attractive, especially in facial designs. Akito is as plain-Jane in design as harem leads normally are and the girls offer a pretty typical range of figures and builds. Much less typical is the clothing, as both Akiko and Arashi wear full stockings (black and red, respectively); in fact, Akiko only really bares her legs when wearing a swimsuit, which is very unusually conservative for a series like this. Beyond the lively opener and closer, the musical score is entirely unremarkable in its effectiveness.

Funimation made big waves by taking the extremely rare (for them) approach of opting not to dub this one. (One has to wonder if they truly understood what they were getting when they licensed it and opted to limit their financial risk, as they had to realize at some point that American fans are unlikely to be as tolerant of the in-your-face incest present here as Japanese otaku might be.) Also highly unusual for them was retaining the original Japanese credits in the opener and closer, with the English credits shown separately after each episode. Explanatory notes about the “ana” joke are included in the subtitles each time it comes up, however, as are a couple of other cases. Funimation still made the series available in a Blu-Ray/DVD combo pack, with each set in its own case and both included in an artbox. Both cases include bonus artwork, with clean character pictures on the outside and lingerie versions of the character on the inside. Aside from the aforementioned omake, the only Extras are U.S. trailers for the series and clean opener and closer. Blu-Ray picture quality is notably sharper than in the DVDs but not a huge improvement, and the DVD menus are actually more easily readable.

OniAi improves just enough in its late stages, and has good enough technical merits, to avoid being a total disaster, but it is still a bottom-feeder amongst recent harem series. The meager entertainment value it does offer is simply not worth the time commitment required to watch it.