These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Audience-Alienating Premise: Koi Kaze is a shining example of this. It's squick enough because Nanoka is sixteen and her love interest is in his late twenties. It gets unbearable when you learn they're brother and sister. Even the most avid Brother-Sister Incest fans stay away from the series as it's too realistic for them.