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.
Memetic Mutation: This page◊ in which Hakuron shows off his martial arts skills to Kurumi has spawned a ton of parody fanart on Pixiv.
Narm: People have laughed their butts off after merely reading plot summaries about this series. Um, yeah.
Special mention goes to the scene where Kurumi donates blood to Hakuron to save his life, and when he wakes up and finds out, he bites open the skin on his wrist and starts licking up his blood, because even though they can't be a couple in real life, at least they can be together inside his bloodstream.
Aside of Shinjou's rapes? Considering that Haou Airen is Darker and Edgier compared to other mangas of hers, the amount of violent scenes can get very high.
Also, no matter what you think of this manga, there is a scene that fits here perfectly: Reilan's bloody death at the end of Hakuron's pistol. The Gory Discretion Shots and their aversions were very well paced and made the scene genuinely terrifying.
So Bad, It's Good: It's actually so cheesy, over-the-top and ridiculously overblown, that some people specifically read it to have a laugh. Oops?