WARNING: Per wiki policy, Spoilers Off applies to Nightmare Fuel pages. All spoilers will be unmarked.
Warning: Do NOT make Rentarou's girlfriends cry note .
- While disturbing enough already in the manga, the vice-principal's creepiness is amplified in the anime. The scene of her kissing some poor student is even worse in the anime, as we're treated to an x-ray view of her tongue in the student's mouth and throat.
- The girls under the influence of Kusuri’s kissing drug are terrifying to see, but the way the drug affects them is no slouch either. Their minds are only capable of thinking about kissing, all inhibitions are deactivated, and if they don’t receive the antidote within an hour, the transformation becomes irreversible. It's made a lot worse by the fact that the affected girls become unnaturaly fast and strong, and they are even shown working together to catch Rentarou, though most of the time they are shuffling in a zombie-like gait after him, which is already uncanny enough. Nano easily takes the cake not just by showing more alertness and intelligence than others, but she eventually ties Kusuri up, rips the door knob out of the door with her bare hands to enter, corners Rentarou and pins him down before going for a kiss. The brief fake credits that come along with the visual distortion glitch effects do not help, either.
- Hahari during the first few chapters of Volume 3 / Episodes 9 and 10. A wealthy widow who's recently found out her daughter is dating an apparent five-timer, and is planning to remove her from his life. When Rentarou tries to take her back, she tries to have him assassinated. Literally, the only thing that prevents her from doing so is Rentarou seeing her face for the first time.
- After the Lie Detector interrogation in Chapter 18, a maid informs Hahari that her daughter is trying to jump out the window. In the next chapter, Hakari nearly falls to her death, only being saved when Rentarou redirects her fall into the fountain of a wealthy family.
- The volume 6 extras reveal that Meme first utilized her Ninja Log trick as a baby when her parents were gushing over how cute she was at the mall. Her parents understandably freaked out and started tearing the place apart. By the time they found her, they were both in tears, with her mother describing it as the most terrifying incident in their whole marriage.
- The pharmaceutical spy in chapter 74. He's the first character to actually visibly threaten anyone's life, being willing to endanger the lives of an entire family to get his hands on dangerous drugs to use for his own unsavory purposes.
- Chapter 84 is notably one of the only times in the manga where Kusuri shows genuine anger. The fact that she's angry at her baby grandmother makes it all the more terrifying.
- After getting stuck in a giant vase and lapsing into infant-mode in Chapter 96, Kishika comes back to her senses after Hahari helps her out of it so she can go to the bathroom. When she comes back and tries to help Hahari out, Hahari attempts to pull Kishika back down with a dissonantly cheerful smile. It's played for laughs of course, but in hindsight being trapped for a long time with someone who can easily enable hidden impulses you can't control is terrifying to think about.
- The Big Cheese of the Publishing Biz, who appears in Chapter 109. A faceless being who approaches Rentarou in his dream and overrules his plan for him and the girls to indulge in Serious Kids Beer, and Rentarou is powerless to protest. He even confronted all the girls in their dreams, too.
- Rin's Imagine Spot of what happens when doing arithmetic to personified numbers in Chapter 130, involving a whole lot of Body Horror as the numbers get forcibly merged together or chopped and torn into pieces. Rin being who she is, she loves it, but it looks gruesome to most anyone else.
- Chapter 132: It doesn't come to pass thanks to Eira's swift work, but a baby very nearly gets run over by a car after getting out of her stroller. A close look at the driver's side of the car reveals that the driver can see the baby and is freaking out. It's little wonder that the driver is more worried about the people he nearly hit than the damage to his car. The baby's mother is understandably in tears as she thanks everyone.
- Shizuka's mother. She played a large part in Shizuka's introverted behavior, and when she finds out that she's using her phone to talk for her, she confiscates her phone, prompting Rentarou to confront her about it. And she isn't one of Rentarou's soulmates, so he can't resolve the issue by having her fall in love with him.
- The youkai that the girls encounter inside the school in Chapter 136 alternate between this and Nightmare Retardant. The next chapter reveals that they were actually members of the youkai research club dressed up as youkai.
- Tama’s situation. Other girls have had problems before, but she is so extremely depressed that she is suicidal, with the Cat Girl thing being a coping mechanism that very obviously isn’t working. If Rentarou hadn’t chanced across her, she would’ve starved to death within a few weeks. And as superhuman as Rentarou is when it comes to pleasing his girlfriends, he’s still Just a Kid and has never dealt with anything like this. He and the rest of the harem are going to have their work cut out for them if they actually hope to improve Tama’s condition. There will probably be lasting consequences instead of all her problems being solved by a kiss.
- Chapter 164:
- The Infinity Shrine's God is the first genuinely supernatural antagonist in the series, and arguably the most powerful and malicious one so far. Twisting Matsuri's innocent wish into a full-on Ironic Hell that threatens to scrub five other girls and Rentarou of any free will, forever, and makes the mother of all Nightmare Faces when she begs him to put it all back to normal.
- Not to be outdone, Rentarou manages to be just as scary if not scarier than the God of Infinity, managing to completely defy the god's power and make his way to the Mugen Shrine because the god made Matsuri cry. The god tries amplifying his power tenfold, but while this initially seems to affect Rentarou, he pulls an Exorcist Head, the once happy smiling looking demented and monstrous, as he proclaims his intent to kill him and burn his shrine down. While undoubtedly a badass moment, the fact Rentarou was able to terrify a freaking god while ignoring his power is the stuff of nightmares, as can be seen in the page image.
