The name does not deceive you, there is certainly a conflict with brothers in this anime, too much so if you ask me. I'd honestly just like to ask why. If not for the spectacular artwork, which is virtually the only thing keeping me from rating this series a "2", this anime would be a complete flop.
Let's just address for a moment, stay with me because it can get confusing— 13 new step brothers. If that weren't bizarre enough (not necessarily saying that bizarre is bad), they all miraculously fall in love with her? I have to believe that the screen writers for this show were absolutely drained of decent ideas. I have no qualms with originality, because this notion of suddenly getting 13 guys to fall in love with you within a few day time span, unless you're Kate Upton, is a new idea for me. Frankly, all girls should be taking notes from Ema Asahina, she's the key to a jackpot of hot guys fawning over you for doing absolutely nothing.
There's really nothing to say about the plot. There was zero complexity. If you happened to miss a few episodes, don't bother going back, just replace one of the brother's names with another, add a few instances of passive sexual harassment, and you essentially have every episode.
I would discuss character, but it leaves a lot to be desired as well. Ema was basically a sex doll for the brother's frustration. Obviously not to that degree of severity, but she had absolutely NO input on anything. She sat by passively while her brother's pushed her around, literally, and force kisses or embraces on her. The only thing she could do was cry when her brother's relationship began to fall apart because they all started hating one another, as they blindly sought her affection. Gee, I guess having illicit relationships with your brothers wasn't such a good idea, surprise, surprise.
I won't lie, the series was enjoyable, simply because the character attraction was high. Well-drawn males who play on their sexual appeal isn't a bad thing, but it wasn't enough to draw an eye from the blatant lack of character development. To sum it up, 13 guys, 1 girl, steamy interactions.
When I phrase it like that, I'm almost tempted to re-watch it... So, knock yourself out.