Nightmare Fuel / YuYu Hakusho

Yu Yu Hakusho, as much as it is a shounen series, let us remember that Yoshihiro Togashi was inspired by H. R. Giger the artist who designed the titular Xenomorph Aliens, and that the 90's was a grand time for a genre best described as 90's Horror Anime. The series' debut came out at a time when lighting helped give 90's anime a gloomy and airy effect for atmospheres, and considering Yu Yu Hakusho's themes of the supernatural, eldtrich, and the infernal, the series also does not skimp out on its genre.

  • Chapter Black. The fact that all of mankind's worst moments, from acts of genocide, to slavery, to even war and destruction of all sorts, unadulterated and uncut, were put on tape, and you could watch real life cruelties and evils committed from all throughout time.
  • Reading into Sensui's Mind. Murota goes insane over the fact that Sensui chants nothing but how much he would like to see piles of bodies, from adults, to children, to the elderly, piled in graves, and butchered in any feasible and possible manner, and gets more and more ecstatic about killing EVERY human.
  • The Anime was darker and less discreet about showing us what on earth could happen should Yusuke and the crew die or fail on their mission, and what on earth they had at stake. And they did NOT skimp out on the details.
    • The Makai Insect infestation.
    • The result of the opening of the entrance to the Demon World. GOOD FUCKING LORDS.
    • Mr. Iwamoto possessed by a Makai Insect, is now free of all inhibitions and microscopic shreds of whatever passes as "morals" he had. RUN, KEIKO, RUN!
  • The Sinning Tree, and Elder Toguro's fate. He doesn't die. He never will. An eternal life under a nightmare and your worst fears to haunt you forever. Give that a thought.
    • Quite fitting in that pretty much everything about Elder is Nightmare Fuel actually, up to and including his death. His Lovecraftian Superpower, creepy head in a fish tank, killing Gourmet from the inside, he probably also ate Murota as Gourmet, even his personality could be considered Nightmare Fuel.
  • Younger Toguro going 100%, it starts off with a gaunt body, compressing the power, it bursts into purple energy that later shrouds the arena in darkness. After which, Toguro greatly enlarges his body (which sounds very painful) through bursting muscles to unnatural extremes, we see a close up of his new muscle skin as well as which appears to be breathing just before the transformation completes.
    • During his No-Holds-Barred Beatdown at the hands of Toguro, he tries to escape into his dreams where he sees himself and Keiko as children. Toguro appears as an enlarged version of himself to grab her, saying its too early to escape into his dreams.
  • During the Sensui fight, there's one pretty unsettling Mood Whiplash Sensui shoots Yusuke, and soon takes a completely different persona. That being a sadistic gunman called Kazuya who gives Yusuke a No-Holds-Barred Beatdown by gunning him down and grinding his wounds, This wouldn't be so bad, if we didn't learn that he was an admitted baby killer and loves the sound of screaming way too much. Thankfully, Koenma shows up before Kazuya decided to blast through Yusuke's skull. Quite a twist from a suave manipulator.
  • Yukina saying that she's searching for her brother to have him commit a genocide, especially with it coming from such a nice girl.
  • Hiei's idea of a nice birthday gift for Mukuro. Actually, this is almost funny in a sick, sick, sick way, seeing as that's the guy who used her as a sex slave, but still...
  • Mukuro was "fitted" to be used as a sex slave when she was just a NEWBORN BABY. In other words, she was raped since age 0. Brrrr.
  • While Kurama has a fancy rose whip, he's capable of summoning man eating plants with acidic saliva, blood sucking plants that literally either burst from the victim's body or drain them dry, and here's the kicker, a plant that constantly drains your life while giving you hallucinations of your worst fears, potentially a living hell for any impossible to kill psychopaths. Yes he is a nice guy.
  • Karasu may be the most nightmarish villain, despite limited screentime, even with someone like Elder Toguro, who was incredibly repulsive and cruel. He is notably the only antagonist that has ever truly frightened Kurama; not Yomi, not Sensui, and not the Toguro brothers, ever managed to unnerve Kurama the way Karasu did, and its not hard to see why:
    • Karasu establishes himself by nonchalantly exploding his foe's arms by effortlessly touching him; laying a bomb inside him, and threatens to blow his victim's legs or head off. When the disarmed and helpless opponent tries to escape, having no method at all to fight back, Karasu coldly murders him.
    • His encounter with Kurama further shows how much he "loves" Kurama, as he snuck up behind him, and caressed his hair, he comes off as a depraved and predatory serial killer. Afterwords, Kurama tries to figure out how to defeat him, but comes to the conclusion that he absolutely had no chance, with an imagine spot of Karasu sneaking behind him, and detonates him; Kurama is enveloped by the explosion and a truly anguished death scream.
    • Then Karasu shows that he didn't need to touch Kurama in order to blast him, really plays mindgames with Kurama, telling him that although his power can't be seen, it is everywhere, even in the air he breaths.
    • Even when Yoko Kurama emerges, Karasu only had to lose his mask, and immediately turned things around, as Kurama was forced to revert back to his human form.
    • Most strikingly is how absolutely calm and nonchalant Karasu is during all this, while almost effortlessly breaking down Kurama with his mindgames and powers. But he does show more open expressions and emotions as he gets excited, usually when he comes very close to killing Kurama multiple times.
  • When Yomi shows Kurama the demon that blinded him 1000 years ago, the (moth?) demon is in a severely brutalized state. His hands have been nailed to the wall, his eyes have been ripped out, one of his horns has been snapped off, he has scars all over his body, his torso is so thoroughly stripped away that his spine is exposed and the only thing keeping his lower body connected with his upper body is a thin strip of muscle tissue. The former assassin is in so much unbelievable pain that he can barely speak, and when he does speak all he can do is beg for death — this is Yomi's idea of punishment for losing his vision. The scariest part? After who knows how many countless years of torture, not once did the assassin ever admit to Yomi that Kurama was the one who ordered his assassination. The reason for this being that the assassin was more terrified of what Kurama could do to him compared to Yomi. This says a lot more about how brutal Kurama was in those days than it does about Yomi's savagery.

http://tvtropes.org/pmwiki/pmwiki.php/NightmareFuel/YuyuHakusho