This review will cover solely anime and not ranobe or manga because I hadnt read them. Story First a very quick summary of whole story. Plot isnt really anything unusual or unique and it hardly develops over time. There are also some parts that could have been used to make things interesting like but it was just presented to viewers as a fact and thats it. To summarize plot isnt exactly the greatest strength of this title. Compared to other series like oreimo imocyo imosae or eromanga sensei you could even say its dull. Animation I dont have much to say about this there arent any scenes where you could say that animation was amazing still its good and normal pleasant to watch. Keep in mind that its 2012 we are talking about. Soundtrack Whole OST is pretty good it didnt distract while watching and added atmosphere. Also personally I really liked the ED its animation fits song really well. Characters This is also a pretty weak point for series because there are mainly only four characters: Akiko Akito Ginbei and Ana. Of course there are other characters but they dont get as much development and screen time as these four. You can pretty easily summarize each character without loosing any important information. None of them are exactly complicated interesting or unique but they are consistent and fit in pretty well. More about plot So if character nor story are developing what is happening in these series? To summarize its a bunch of different girls have funny cute and romantic interactions with Akito and sometimes even competitions or fights between them while his sister is pouting and trying her best as well. Through these interactions we slowly get to know character because we dont have a clue about their stories but thats it. How does it feel? So after reading all these points you might wonder what is the point of watching something like this? Story where every aspect is average or below average this doesnt look good on paper at all. I will try to explain what I liked while watching this anime. Overall OniAi is pretty simple sliceoflife romcom anime but you know sometimes all you need is just a little sister who really likes her brother. While watching this anime you dont have to think much about whole plot or what does some character think you just lay back and enjoy cute and funny interactions between brother sister and all different kinds of girls who try to win her brother over or simply just save her brother from his sister all this with fine animation and soundtracks. Although sometimes it does get boring and you wanna take a break from watching it. Would I recommend you to watch it? Most probably not. If you want to watch anime about little sisters there are a bunch of other options that are much more interesting and entertaining than OniAi. Still if you think that you already watched most of them and you want to watch something simple and average OniAi might be your choice but if you watched few episodes of it and think of dropping I think its best to do so because its pretty much consistent and wont change much with next episodes.