Saint Seiya: The Lost Canvas/Nightmare Fuel

Saint Seiya the Lost Canvas is arguably Darker and Edgier than the original series, which by itself was a plateful of Nightmare Fuel. Granted, it's said to be the most violent out of all the battles against Hades, so you should expect some bloodlust and many deaths of important characters. And it is a war against the ominous god of the Underworld and his equally nefarious underlings (well, most of them), so you really should expect some extent of dread and creepiness.


 * The entire arc in the Forest of the Dead is made of this.
 * Yato is tricked into believing his friends were killed, seeing an illusion of their mangled corpses... about to be devoured by some kind of giant monstrous centipede.
 * Nasu Veronica manipulates the corpses of anyone buried in the area engulfed by the forest; initially, he uses the decomposing bodies of Tenma's orphanage friends, who died in their childhood, to attack him, knowing he wouldn't be able to bring himself to attack them. When faced by Tenma, Yato and Yuzuriha, Veronica raises an entire army of corpses.
 * The child zombie biting Tenma's neck and ripping off a chunk of flesh, leaving a bloody mess, is something disgusting to watch.
 * Garuda Aiacos's men being set aflame and burned alive on-screen. Leisurely. By their own boss.
 * Sphinx Pharaoh's insane troll signature attack, consisting on ripping off the target's heart and weighing it against the Feather of Maat. If it's heavier, the target is burned alive. If it's lighter, the move does nothing else to the target; too bad their heart was already ripped off and they can't live without it. Visually, it's not very nice seeing hearts violently taken from their owners' chests (and their potential immolation).
 * Wyvern Rhadamanthys.