Emma and Norman coming across Conny's corpse and realizing that despite their peaceful life, they were essentially being raised so they can be slaughtered like animals for food.
The scene with the demons is somehow even more terrifying than the manga. It's the way they move, and those eyes.
Emma asking Ray how many people he's sacrificed in his experiments in order to escape the farm. He admits that he had to get his hands dirty in order to get his plan to work. While Emma says she's fine with what he did in the past, she's understandably pissed when she tells him that if he tried anything like that now she would most certainly never forgive him.
The double back-to-back whammies of Krone being fed to the demons in a hopeless fight, followed by Isabella showing her true colors to the main children - and breaking Emma's leg like a twig in the span of three seconds.
Ray at the tip of insanity decides that in order to get their plan of escape started he would set himself and the house on fire. He declares that he wasn't going to become food and he would die like a human, and even Emma's face seems to be wondering how far Ray had fallen into this kind of despair.
In order to disable the tracker and make their escape, Emma and Ray are now missing one ear. They're both extremely steeled characters, but what kind of pain did they experience when they went through with cutting off their own ear?
Isabella has to essentially raise her biological child Ray as food for the demons.
Discovering the animal corpses in what seems to be a safe, idyllic underground grotto in the woods drives home how even the landscape is against the escapees and the world is nothing like old Earth anymore.
In chapter 47 we finally learn what happened to the world 30 years ago: nothing. The world had belonged to the demons centuries before then, and the real story behind the plantation isn't much better. After years of war between the two species, leaders from both sides came to an agreement to end the bloodshed. The world was divided and the plantations were glorified parting gifts from the humans. Whether the parents had any say in it or not, someone had the idea to willingly give the demons children with the sole purpose of raising them as livestock.
As of chapter 49 Emma is learning to hunt, or as she puts it, "to take a life." While the main reason was just to make it easier to get food, the fact that an eleven-year-old feels the need to learn how to kill in order to survive speaks leaps and bounds for what she might have to do in the future. Doubles as a Moment of Awesome depending how you look at it.
Chapter 50 gives the positively wonderful sight of the other plantations in the demon world. Turns out Emma, Ray, and the others were the lucky ones. Only four out of the several hundred plantations were "premium models", the rest are demonic versions of Factory Farms, and it only gets worse from there. The kids are strapped in place and food and body fluids are siphoned in and out through tubes, and its implied that they've been like that since birth. Remember when demons and humans alike refer to the collection of humans for consumption as a "harvest," a term usually used to refer to plants, not animals? The way these children were raised is closer to how you'd grow plants than raise livestock.
It gets even worse on a psychological level. These kids don't even get the illusion of a happy childhood like our main cast did. With their entire lives literally just spent fattening up, they're barely a step above braindead. They don't know whats going on, they can't move, they can't even speak. They're just stuck in a mental limbo until they're "ripe" and get sold as cheap, mindless, livestock; the only thing they can ever really be called.
Goldy Pond, the next area Emma believes is Minerva's location, is a secret hunting ground used by demons. Not even the farms know about it!
What's worse is that we actually get to see them kill and eat their spoils. Thankfully the preparation part is offscreen, but it's still immensely disturbing to cut from a demon beheading a boy to a lavish "steak" dinner.
Norman is alive and in an unknown location. He's deduced it seems to be a more complex farm, which has its own implications, but there's the fact that he passes by this.◊. The fact that some of the kids look like they've been lobotomized is horrific on its own.
Most of those kids don't even look HUMAN, that's how messed up they are.
This is what the demons look like without their masks. Trypophobes and ommetaphobes beware.
What makes it worse is how... expressive their faces are, despite being totally inhuman.
When Louvis' mask breaks, he pulls out all the stops. His thrill for the hunt turns him into a psychotic maniac, finally getting the prey he's been hunting for so long.
You think that the kids are out of the woods? No. As it turns out, it's not only the "demons" they have to worry about anymore, but the humans who want to keep the peace between them and the "demons" and they will do so by killing everyone.
Chapter 111. Just...wow. Not only is the leader of the squadron sent to kill the "cattle children" still alive, not only did he manage to kill three of them, but he's somehow still alive and talking despite missing a good chunk of his face and head! Talk about determined!
The bastard's death in Chapter 112 is both nightmare fuel and awesome at the same time. He gets eaten by one of the feral "demons" and he's screaming the whole time.
After reuniting with Norman he tells the group his plan the secure the future for the humans in the demon world.... and it is basically genocide. The kids are happy (its likely that they don't fully understand) but Emma less so.
Chapter 120. We finally learn who the "demons" are and why they eat humans. They were once formless creatures that consumed the animals and plants around them, taking on their traits as they ate. Then they began eating humans and became intelligent, cultured, and gained the ability to speak. The problem? The "demons" soon discovered that if they stop eating humans, they will revert back to their savage, primitive state. Those "feral demons" the children encountered in the wild? They were the ones that didn't get enough humans to retain their intelligence. That's why the "promise" was made. To keep the demons from reverting back to their primal states.
There is another problem. The cheap factory farm children aren't enough to increase a "demon's" intelligence and if they stop eating, they eventually revert to their primal state in just six months.
Remember the lab Norman was in? All those deformed children just like Adam? It turns out that Lambda is a facility that performs genetic experiments on humans to make good quality meat in the mass production farms. Norman intends to use them as part of his army to take down the "demons" and destroy the farms.
Emma wants to make a world of peace that won't involve bloodshed, but there's a slight problem. Everyone is on board the "kill all 'demons' train" and it seems the people Norman is involved with do not like her idea. They react very angrily when she shows signs that she doesn't want death on both sides of the game. Emma is afraid of these people probably even more than the "demons". Heck, she and Ray become afraid of what Norman is planning.
Norman's reaction to Emma's revelation about Sonju and Myusica still retaining their intelligence despite not eating humans for hundreds of years. He calls the latter the girl with cursed blood and demands to know where she and Ray met them. Something's not right the way Norman practically orders her to tell him.
Chapter 127: Norman reveals that Myusica is actually from a clan of "demons" whose blood has the unique power of giving a "demon" a permanent human form and intelligence and would never have to rely on eating humans again for the sake of preventing themselves from devolving. Moreover, those who consumed the blood gave birth to "demons" who also had permanent human intelligence. However, the "demon" royals and five regents and the Ratri family saw this as a threat to the farm systems, their money supply, their control over the "demon" world and the promise they made, so the royals and five regents devoured the cursed blood "demons" until only Myusica remained.
While explaining her unease about killing all the demons, Emma vividly imagines what would happen to a demon village she visited earlier in the story if it was cut off from human meat - all of the inhabitants, who were so humanlike in their family structures and habits, going feral and turning on each other, eating their own children.
Chapter 128: Whatever the experiments did to the Lambda kids causes them to have fits and very severe headaches that require them to take medicine. They seem to occur when they experience extreme anger.
The Lambda kids are so full of hate toward the "demons" that they did to the "demons" what they did to them. In their room, there are jars full of "demon" organs and other body parts and they even keep the corpse of a feral "demon" as a practice dummy.
Norman has become a Knight Templar, showing no regrets for his actions and is fully convinced that Emma's plan for no bloodshed will never be enough. The final page shows an image of himself as half a grim reaper and half an angel as he calls himself both a God and a Devil for the sake of saving all humanity and killing all "demonkind".
Chapter 131: We meet the ruler of the "demon" world herself, Queen Regula Valima. You know she's trouble when all five heads of the Five Regents bow down to her as soon as she steps into the room.
Chapter 133: Emma and Ray's hunt for the Seven Walls brings them back to Grace Field, but it's not the same place they knew. It's full of Alien Architecture that sends them all over the place. Ray runs into a hallucination of Isabella and several other kids all based on ones that were eaten, then they start turning into skeletons. Turns out it was all caused by the Demon Boss (with the unpronounceable name) "playing" with them.
Chapter 139: It turns out Norman not only sent Don and Gilda and Aishe to go look for Musika and Song Joo, he also has the Lambda children tracking them down with the intent to kill the cursed blood "demons".
Chapters 141-42 reveal the origin of the first promise. The war between humans and "demons" lasted for centuries until one knight, Julius Ratiri, grew tired of the senseless human bloodshed and wanted to make a truce with the "demon" god. But when he told his fellow knights of the promise, they immediately went against it, so what does he do? He labels them the first human cattle and has the "demons" sic on them.
The chapters also reveal that the "demon" god wants a little something in return for the promise. From the "demon" royals, he gets more human meat than they. And as for Julius, he and his descendants are forced to be the keeper of the promise, to make sure it is never broken.
The first chapter and big reveal were horrifying to read but made even more so in animated form. The demons are meticulously animated to the point its unsettling to watch. You can see poor Emma and Norman struggle to hold back their terror and shake uncontrollably when they realize the truth of their home.
You wouldn't think a shot of somebody going upstairs would be unsettling, but put it in first-person perspective... the anime staff clearly love their horror movies.