Just watched 1-4 of Koi Kaze.
I feel like I've just spent 80 minutes watching something and nothing has happened. There's been the character introductions and we've got to the stage where Koshiro is sniffing his sisters bra/masturbating about her...that's it.
Koi Kaze's story is about two siblings who weren't raised together starting to live together with their father due to Nanoka (the 15 year old girl) moving in to be closer to her new school. The brother and sister feel emotions for each other that are certainly not just brother and sister feelings, resulting in much awkwardness on the part of Koshiro, her 27 year old brother.
The story about incest isn't really disturbing, I'd call it more unusual. They hadn't grew up together and managed to spend a few hours at an amusement park before they discovered they were family, where they discussed how they both had recently had their hearts broken...or, in Koshiro's case, broke up with someone he had no feelings for - It's not too shocking they don't have brotherly/sisterly feelings for each other. The most disturbing aspect of the story is their ages, Koshiro being 27 and Nanoka being 15 (15 is actually legal in Japan).
Koshiro spends most of the first volume hating himself for feeling like he does about his 15 year old sister. He first attempts to be nasty to her when he discovers she's his sister, eventually stopping when his sister reveals the obvious by proving he does care about her, before starting to act more friendly towards her as the volume progresses. The volume ends with Koshiro starting to give in to desires by masturbating about her, followed by him smashing up his room in anger/disgust at himself.
I'm not really sure about the series at the 4/13 mark. It's slooooow, the art/animation isn't amazing, there's no stunning music... Nothing special. The only thing it has going for it right now is the unusual plot.