First of all, Koi Kaze lacks all those annoying anime clichés that usually put me a bit off when watching a series. There are no girls who are supposed to be 15 but act like they are 10 and speak with the voice of a toy rabbit. Instead, we get a realistic portrayal of a teenage girl who actually acts naturally. Nanoka's voice actress does a brilliant job, she sounds natural, like she is acting with her own voice instead of making up a voice for the character. The character designs are also more realistic, with the characters looking a whole lot more like real people than most anime characters. Everything is kept serious and realistic in general.
Koi Kaze is not a noisy or action-filled series, but it's never dull either. As the story progresses, the viewer will sympathize with both of the two main characters, even though they in no way are perfect. They are two people, brother and sister (and the brother is significantly older as well), who are gradually falling love, and they can't help it. It's difficult, even painful, to watch, and it does make you think about what is to be considered "right" and "wrong". Before watching this I thought the concept to be clearly on the "wrong" side, but after watching it I concluded that I'm actually in no position to write off a relationship as such.
The music is also worth mentioning. It's not loud or dramatic, but rather simple and effective. There are a few beautiful piano pieces playing that do a very good job in setting the mood. The music never takes the focus off the story, but complements it very well.
All in all, this is a series I would recommend to anyone, heck, it might the single series I would strongly recommend even to those who don't normally watch anime. It's been a good while since I watched it, but the story never left me and it makes me want to come back and re-experience it. With absolutely no traditional melodrama or "in your face" symbolism whatsoever, Koi Kaze manages to touch, to shock and to offer something new to the viewer, and it's a story you just don't forget. It's that good.
