* CompleteMonster: Cain. He's raped and murdered hundreds of innocent people, watched as a newly transformed Shido slaughtered his hometown in a feeding frenzy and then erased Shido's memories to the point that he couldn't remember his own name, tortured a reluctant Nightbreed who was in severe denial and only wanted to see her lover back from war, fatally slashed Riho after he believed her to be a rival for Shido's affections and trapped Shido in an illusion where his worst nightmares of pain and loss came true.
* DieForOurShip: There are those who don't exactly care for the Shido-Riho pairing.
* EvilIsSexy: In episode 12, after Riho leaves Shido, she starts dressing in a slinky black mini-dress.
* FanPreferredCouple: Apparently, there are those who would ship Shido with either Yayoi or Cain.
* FreudWasRight: When Cain forcibly feeds Shido blood in a flashback in episode 12, it looks a lot like a rape in progress . . .
* MagnificentBastard: Cain, once you realize that by having Shido and Riho in a happy relationship together as vampires, it makes it more likely fo Cain to inlfuence Shido in a century or two.
* MoralEventHorizon: In Episode 12, after Riho kills Yayoi and Guni, Shido feels he has no alternative but to kill her.
* OtakuOClock: "Nightwalker" was one of the first late-night anime series.