The main character and one of the last remaining werewolves, Inugami has drifted through life on tides of misfortune, carrying a disdain for humanity and an uncanny ability to avoid death. He strikes up a bond with his new homeroom teacher, the kind and beautiful Ms. Aoshika, despite himself and what he's gone through. So, Inugami goes through the story facing characters that seem to lose themselves by his sheer presence, and trying to make sure that his bad luck doesn't rub off on on Ms. Aoshika.
The Hero Dies: Inugami dies after doing the impossible to kill Haguro, Aoshika mourns in despair, and his aunt keeps her company while she gets to know more about his life; still if this is going to stick is another story...
True to some cases of this trope, it didn't stick, as soon as Aoshika knew all about Inugami's past and found a new resolve to recover, Inugami is seen at a lab, being healed and being a subject of research.
Hot for Teacher: The only (living) person he shows affection to is Aoshika-sensei. Guess what happens soon...
Lady and Knight: The (very furry, bitter and hurting) White Knight (sorta) to Aoshika's Bright Lady.
Last of His Kind: Subverted. He thinks he is, but it's revealed that Akira Jin is also a werewolf.
Locked into Strangeness: by pulling Heroic Second Wind one after another, Inugami's hair turned white, his werewolf form also became white, it simbolizes that he was taking energy from his own life to protect Aoshika and defeat Haguro.
A troubled middle school teacher, who is saved by Inugami from a gang of thugs. She's somewhat nosey, more interested in proving herself right that Akira Inugami is a werewolf and less in that she's dealing with a werewolf, but is otherwise genuinely worried for her student's mental wellbeing. Concern turns into more complicated things, especially when their student-teacher relationship warps and she falls within range of Inugami's magnetism for mayhem.
Tropes that apply to Aoshika:
Beauty Equals Goodness: The most beautiful person in the manga and one of the few with a fully-functional moral compass.
Broken Bird: Seems to have rape in her Back Story. She gets even more broken later on, specially when Hagurou decides to use her as bait for Inugami... as well as having her gangraped. Repeatedly.
Christmas Cake: Although she was married once, but got divorced recently. She lampshades it in her drunken rambles before she meets Inugami.
Gag Boobs: Ms. Aoshika's so well-endowed it's almost silly.
Fan Disservice: Seeing her in her lacy undies should be a reason to squee. Not when she's chained to a wall, and about to be brutally gangraped by Haguro and his goons.
Happily Failed Suicide: As if being gangraped, drugged and recorded throughout the second half of the manga wasn't enough to push her over the edge, her before her much-needed rescue, Aoshika tries to jump off the hospital's terrace when she hears about Inugami being dead; she is stopped by a wolf who resembled Inugami, and she realizes that he could be alive somewhere and that she has to live in his place and honor; in truth the wolf was Jin, Aoshika discovers this by herself and talks to Jin in Alaska about it, thanks to this she now can recognize each wolf individually and finds a new respect for them, that's where she decides to live in Alaska.
Throw the Dog a Bone: Aoshika finally seems to experience a true recovery this time, after getting to know about Inugami's past, she decides to live in Alaska, at a preservation site, where Inugami was raised by wolves. The wolves accept her presence and starts to know them better, her body is looking healthy and she is smiling again, also she seems to know wolves so much now that when Inugami woke up at the Phoenix Organ lab, Aoshika immediately noticed something.
Yank the Dog's Chain: Great, Aoshika is saved, but at the moment Inugami is taken for dead; which made Aoshika sink deeper than when she was getting gang raped, she is not eating anything at the hospital, she can't take Inugami off her mind, and now her body shows signs of malnutrition.
Younger than They Look: With everything that happened to her between her kidnapping and rescue, the poor woman has visibly aged quite a bit by the end of the series.
The scariest ninth grader you'll ever meet. Son of a Yakuza, who develops a... fixation on Inugami sparked by their being near total opposites. Where Inugami is a deliberately passive physical monster that gains a Morality Pet, Haguro is a destructive human being that abuses those closest to him. As the story progresses, this contrast becomes more stark and he grows the more monstrous of the two. Which is his whole intention: to be a true monster. A werewolf around just means he'll have to kick it up a notch. Or twelve.
Animal Motifs - A hawk. Special mention goes to his eyes, which are black where they should be white.
Attention Whore: His motives are best summed up as "How the hell can I get that werewolf to look my way?!" And he persists in this behavior even when his resources would be better spent doing anything else.
The Dreaded: Students have a massive Oh Crap moment when they hear he is coming back to school.
Evil Cannot Comprehend Good: Subverted in one case. Haguro quickly figures out Inugami has at least one altruistic bone in his body and goes after Aoshika. Played straight in that he wants to be Inugami's Worthy Opponent but doesn't understand what would make Inugami think such a thing about someone.
Younger than They Look: He's roughly two meters tall and looks like he's in his late twenties. Lampshaded by Inugami in chapter 11.
Haguro's very beautiful, but also extremely messed-up girlfriend. Her interests include destruction, sadism, brutality, and having sex with the man that can deliver the most of all three, so long as it's not in her direction.
Ax-Crazy: Whatever your definiton of "crazy bitch", she's proabably not far off. If she is, you're trying too hard.
Broken Bird: See what repeated rapes from her dad and a pimp and living in a Crapsack World can do to a teenage girl: leave her broken and insane.
Death by Sex: Save for Haguro, the men who sleep with her are all dead. Including her rapist dad and the pimp. After Haguro's death, Ryuuko goes into a kill frenzy, she stabs to death two men who were having her "services".
Eye Scream: Haguro punches her in the eye at one point.
Fan Disservice: She's very attractive and knows it, but she's so deranged that no amounts of nudity from her can count as sexy...
Chronic Hero Syndrome: Jin explains to Aoshika that werewolves can sense a human's sadness or call of help, while no other human can; and in some cases the good ones feel obligated to help the human, or at least try to ease their pain a bit. That's what Jin does for Aoshika, helping Inugami to rescue her and later pretending to be Inugami in wolf form to give Aoshika the hope that he might still be alive.
Even Evil Has Loved Ones: They care about each other. When one of them is told that the other has died because of Inugami (A lie. Haguro was the one who killed the twin.), the surviving twin only hesitates to claim vengeance because he lacks resources. The moment he has some, he tries to destroy Inugami and the school.