Medaka Box builds itself on parodying, homaging and deconstructing various shonen tropes. However what with the meta nature of the manga and the high abundance of Nightmare Fuel you see in the other shonen that it's dedicated to referencing, it was inevitable that Nightmare fuel would make it's way into the series.
- Kumagawa, in-universe and out. In chapter 64 he manages to make the act of eating taiyaki creepy. That's how scary he is.
- Prior his HeelFace Turn, he could be very unnerving.
- Shiranui seems to be an extremely cute girl with an ahoge, but she has flat out said she enjoys following Zenkichi and the crew around because he keeps getting beaten up, and has tricked him into getting mauled by a giant wolf, as just one example. The look on her face when she refuses Medaka's offer of being vice president is pure Nightmare Fuel.
- Medaka can be quite... enthusiastic when improving people. Especially after the Successor arc, she shows no hesitation in wanting to fight Zenkichi without any remorse beforehand. It clearly shows just how unnerving her behavior is.
- Several of the faces War God Medaka makes during her Unstoppable Rage against Myouri.
- Unzen in general is pretty unsettling due to being a Creepy Child with no problem with killing.
- Iihiko tops them all. Managing to scare frickin Anshin'in of all people and taking it a step further by killing her with one hitusing a rubber band. His creepy demonic appearance and his ability to negate everyone else's powers are not helping.