Given how the show dabbles with spirits and supernatural abilities, it only stands within reason that we witness the dark side of those concepts and how our heroes overcome them.
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- While the series can veer into scary territory pretty suddenly, nothing stands out quite like Keiji Mogami. In life, he was a powerful psychic who wound up taking up assassinations for money. After arranging his own suicide, he became an immensely powerful evil spirit, not only being strong enough to torture Mob, normally a Comically Invincible Hero, in a Lotus-Eater Machine for what he perceives as six months, very nearly succeeding in convincing Mob of his worldview in the process. Several arcs later, when his container is destroyed, those on the scene who were there for his debut arc continue to treat him like The Dreaded, when most villains become less frightening after their debuts. He's also one of the only times anyone has outright killed human characters, albeit a bunch of Red Shirt fake psychics.
- At the beginning of the Claw Arc, Mob returns home with Dimple to find his home ablaze. While Mob runs through it looking for his family, Dimple informs him that there's evidence this was a break in, only for Mob to stumble upon what seems to be the massacred and torched remains of his family. While it's summarily revealed that it's an illusion by Dimple, for a brief minute Mob's explosion counter spikes to well over 100, eventually settling on ???%. While he's still awake. The implications of this are chilling — not only is Mob able to consciously access ???%'s power while under extreme duress, but he's able to willingly use it against people if they hurt his loved ones, going against everything Reigen taught him. One can only shudder to think what would happen in a situation such as this.
- The anime plays this up even further, with Mob's Japanese voice actor letting out a downright hellish growl of impotent rage. The image of Mob's bloodshot eyes staring at the fake corpses of his family is the image the episode ends on, and coming from the sweet-hearted Mob, his expression of pure hate is absolutely terrifying.
- Udo, a childlike esper employed by the government, becomes pretty creepy once he activates his Psycho Steroids. He becomes a Tiny-Headed Behemoth that chuckles as he throws around Megaton Punches.
- Dimple's disguise as Lord Psycho Helmet is incredibly uncanny in the anime. While in the original webcomic, "Lord Psycho Helmet" is just a crude and simplistic approximation of Mob's appearance, in the anime, his disguise is much more detailed to show its origins as the Giant Broccoli's roots, with said roots making him look like a shriveled-up corpse.
- Dimple's brainwashing of Seasoning City as depicted in the anime is downright disturbing, particularly in how quiet the transition is. It's particularly horrifying when Reigen finally falls under Dimple's psychic thrall, in part because he wasn't brainwashed through an infectious source such as candy laced with the Broccoli's essence like how it was depicted with other characters. We just hear Reigen's vocalized train of thought gradually and almost naturally transition from thinking the Giant Broccoli needs to go to thinking that Lord Psycho Helmet might not be all that bad a guy to him casually telling Mob that it would be better if they didn't destroy the Broccoli. And the entire time, he's saying these things in his typical "Reigen" way, making it sound like these ideas are coming from him rather than him just acting as another one of Dimple's mouthpieces.
- The Giant Broccoli taking on its own life as "Lord Psycho Helmet", especially in the anime where its swarm of avatars are given zombie-like movements. And then there's the fact that every clone utters the same phrase on loop, "Hand [Mob] over..."
- Chapter 100.2 shows Mob's ???% so single-mindedly focused on getting to their meeting with Tsubomi that it doesn't care about its powers causing windstorms and earthquakes that are cause for concern enough to evacuate Seasoning City.
