- The birth of the wasp, with the person rapidly aging and ending up as a shrivelled corpse.
- So far it's happened to three people, one who died off screen. Shion's co-worker is bad enough, he collapses back and looks at his rapidly ageing hand in horror. We then get a blurry POV shot of him looking at Shion, and he shakily asks "what's happening to me?". The second victim is far more horrific. She first notices the black spot on her face in a shop window, meaning that she's able to witness exactly what's happening to her as she rapidly ages and dies.
- Also happens in a freaky scene to a woman at the end of chapter 10.
- During the Holy Day celebrations the bees go one step further and...well, kill about a fourth of the No.6 inhabitants.
- The pile of corpses in Episode 10 and Shion vomiting upon seeing them. There are live people strewn in the literal mountain of bodies, moaning and groaning enough to nearly break Shion.
- Small, horrific detail: the knitting needle Shion absently grabs onto while climbing that pile. Even scarier in that it's never overtly alluded to, as it's overridden by the horror of the climb in general...
- The whole concept of No.6 - being watched over day and night by your ID bracelet, which allows the higher-ups to see and hear everything you do and say. The worst part? You're absolutely okay with it, because you've never been given any alternative.
- It's pretty small, but Nezumi's reaction to the possibility of everyone dying in No.6 because of the wasps is to dance with Shion in joy. Nezumi's reaction becomes scarier after Shion says that he wants to make a serum to destroy the wasps - he gets angry and threatens Shion because he doesn't want Shion to help them.
- Chapter 13 features Safu waking up in the correctional facility after being kidnapped and finding herself strapped to an operating table. A man tells her that they are going to operate on her and she cries Tears of Fear in response. *shudder*
- Anytime Shion's Yandere side shows up.
- The fate of the people from the slums who are dumped into the room with the dead bodies - if any of them survived the fall like Nezumi and Shion, they are trapped down there with no food or water, surrounded by corpses. Logically, that would lead to rather desperate measures.
- The manhunt. It must have been like pure hell.
- The novel series features a glimpse of Shion working to rebuild society after the fall of No. 6. Perhaps unsurprisingly, Yoming is trying to push everyone who wasn't a member of his revolutionary group out of the reconstruction committee, which is supposed be made of people from all sections of the city. Shion's response is to accuse Yoming of misusing state funds and remove him from the committee. Yes, Yoming did it, but Shion forged the evidence to get him to confess and concealed the crimes of two of Yoming's accomplices as a reward for their assistance. The parallels to the original creators of No. 6, who started as idealists but ended up creating a dystopian society, can't be ignored.
Nightmare Fuel / No. 6