As a Moments subpage, all spoilers are unmarked. You Have Been Warned.
Well, that's not something you see every morning...
The story is filled with Nightmare Fuel. Here are the ones that take the cake.
- The very concept of the parasites is terrifying. It's like The Thing, only a hundred times worse. Someone you know, love, and care about could become the host of one of these things and there's absolutely nothing you can do to stop one from taking over your body unless you're insanely lucky like Shinichi was. And then they'll go around in your loved one's body, killing and eating people — including you and other people you care about with some of the most disgusting Body Horror you can probably think off.
- The (in)famous scene in the first chapter where a parasite-controlled middle-aged man opens up his head, revealing several eyeballs and a multitude of fangs, and then proceeds to bite his wife's head off. If that wasn't nasty enough, the anime puts it at the very beginning of the first episode. See for yourself to the right!! As if that weren't bad enough, that man had a daughter. The scene cuts away when we see him responding to her call from the other room.
- Kana's death is tragic, but then the scene focuses to a distraught Shinichi — who suddenly shifts into such an immense Unstoppable Rage that Migi is unnerved once he proceeds to utterly rip out another Parasyte's heart.Shinichi: Migi. (Death Glare) Handle the defense.
- The flashback scene to Uragami's horrific crimes and his own twisted philosophy about killing.
- Some of these crimes are so graphic and gruesome up in the manga that the anime actually omits them from being seen. One of them includes the all-over mutilation and sexual assault of a CHILD.
- Uragami himself, period. He's a serial killer, but goes past the sociopathic tendency of seeing nothing wrong with his actions. He knows he's killing people and knows it's wrong, but he kills people, anyway, because he enjoys it, it's fun for him. The parasytes may be horrible creatures who can cause horrible things to happen to their host body, but Uragami is human, which reminds you that people like this actually exist in the world.
- Tamura blithely stating her intention to eat her baby or experiment on it if she finds no use for it once it's born. Thank God Humanity Is Infectious.
- Shimada's rampage at Shinichi's school. It makes Mr. A's previous attack look tame with seventeen people dying. Shinichi narrowly escapes with Murano just ahead of Shimada with two students who run getting killed just around the corner.
- When the authorities and military mobilize against Hirokawa and the parasites, their initial attempts to control the cull without harming civilians goes to hell, and in the end accidentally kill various civilians in the process. Yamagishi, the man in charge of the operation, is not only barely phased at all about this, but he orders anyone on the upper floors of the building as shoot-to-kill to prevent even one parasite escaping, and outright kills a parasite without even bothering to guess or check if it was human first.
- Not to mention that when Uragami sees Gotou, he initially dismisses him as just another person to shoot like the squad had been doing. Then he realizes what he's looking at. The serial killer that usually only got serious or annoyed at seeing parasites previously utterly loses his shit and can only flee in terror from Gotou.
- The creepy skeleton creature Migi takes the form of in Shinichi's dreams.
Migi: Looks like someone's terrified.
