In a minor scale, but still relevant, the gang rape scenes, are a Deconstruction of the Netorare concept, showing how utterly WRONG is.
Arc Fatigue: Is Ms. Aoshika still being raped? Yes, and we all want it over with. And only at chapter 97 does Inugami finally reache Aoshika.
Complete Monster: Haguro Dou starts the series as a brutal delinquent and Yakuza heir who thinks nothing of carving a cross into the back of the young werewolf Akira Inugami for defying his authority. Haguro murders the twin brother of one unstable student and manipulates the latter into a shooting rampage at school that kills numerous students and teachers. Steadily growing more and more unhinged and obsessed with Akira upon learning he is a werewolf, Haguro violently assaults his loyal subordinate Chiba for the crime of simply talking to Akira, biting out Chiba's tongue and raping and beating him. After killing a revived Chiba, Haguro blasts the school with a grenade launcher himself before learning that Akira is in love with his teacher Akiko Aoshika. Haguro promptly has Aoshika kidnapped, rapes her and allows his men to gang-rape her after injecting her with a drug to force her to enjoy it to break her further while uploading a video of it to the internet to permanently destroy her reputation to lure Akira to his lair, kill and cannibalize him, Obsessed with proving himself Akira's superior, Haguro represents the absolute worst humanity has to offer.
Esoteric Happy Ending: Aoshika is in Alaska, hanging with the wolves and other wolf men. Inugami wakes up in a research lab, his body still maimed from his encounter with Haguro. Somehow, their spirits end together.
It's also (seemingly) implied that Inugami's sheer force of will is going to help him escape the research lab, and that it is his "destiny" to reunite with Aoshika.
All of this is not even getting to the fact that literally everyone who had ever been involved with Inugami, from Aoshika, to Ryuuko, to all of Inugami's student friends, to Aoshika's fellow teachers, end the manga worse off than they were before, with physical, mental, emotional and psychological scars that will follow them forever, with Ryuuko in particular having apparently gone murderously insane. Only Aoshika has any chance at happiness, and that's assuming Inugami reaches her.
Foe Yay: Haguro gets a bad case of this after Inugami scares the crap out of him with his werewolf state. In a very twisted way, Inugami is the first person to ever wrench a real emotional response (fear) from Haguro; this apparently opened the floodgates in the formerly emotionless and sociopathic Haguro.
Haguro is damn near the epitome of this trope. Having violent sex with his girlfriend Ryuuko and having an orgasm while screaming Inugami's name? Anally raping the hell out of his male subordinate while, again, thinking about Inugami and how this is a punishment for him? Brutally raping Aoshika while recording it so that Inugami can see, practically talking to the camera (and, therefore, to Inugami) through the entire thing so that Inugami will come back to him? The only thing that's missing is for Haguro to actually try to rape Inugami himself, and pretty sure he's working on that one as well.
It becomes downright canon when it gets spelled out that Haguro felt "love at first sight" when he saw Akira. He then becomes obsessed to "become one" with him to the point he throws himself onto his own sword just to be able to hold Akira.
"Holy Shit!" Quotient: We can argue that the HSQ steadily began to rise when Inugami got stabbed by Ryuuko but commenced asskicking his way to Haguro's hideout despite not having the a full moon to power him - but he broke all the damn rules in the friggin' book. The HSQ has reached its maximum in chapter 109-110 when Inugami is getting practically dismembered by Haguro, but not only manages to transform into his wolf form, but into a pure white wolf that was pretty much powered by love, in which he finally kills Haguro, but not before making his psyche totally crumble when he has a quasi- "Freakiness Shame" moment when he sees Inugami in his white wolf form. Phew.
Moral Event Horizon: It's difficult to find one for Haguro Dou, but beating Chiba within an inch of his life, biting off his tongue, and then raping him for good measure would be a good start.
Recent events have made sure he grabs the line, beats it to within an inch of its life, dances over its body. And then rapes it. Just ask Aoshika.
Narm: Sometimes, the dramatic words said in giant block text come across as rather funny than serious. Then again, that's what made this troper like the series a bit more.
There's a scene in which Aoshika has a spiritual moment where her soul becomes in touch with nature... and she's completely naked. Since her chest size surpasses Gag Boobs proportions, this scene appears rather quirky, rather than meaningful.
Also, how everyone speaks, "yer", "ya", "fark" and many speech patterns, they ruin the effect. We know they're teenagers and try to sound cool, but it gets laughably bad in such a serious manga such as this. Moreso if you're not a native speaker and English is your second language.
Nausea Fuel: We may be able to handle one or two chapters of horrific rape, but over ten chapters of it??!! Oh my!
The Untwist: Was anyone else not shocked that Akira Jin was a werewolf?
Values Dissonance: The Defiled Forever trope is discussed/invoked. Aoshika's inner dialogue makes it seem as though the violation of her honor is worse than the actual rape. Understandable, due to Aoshika's past as a rape victim and how she was drugged by Haguro during her rape, specifically to screw her up even more.