Katekyo Hitman Reborn/Nightmare Fuel

Remember, no matter how silly they look like, these people are The Mafia and the worst part? They can use magic.

Pre-TYL arc

• The usage of the Dying Will Bullet. The anime is kind enough to allow the effect of the bullet to hit Tsuna with no visible wound; the manga on the other hand shows that Tsuna IS shot, visible wound and blood flow included, it is TOO convincing.
• Birds. Hoo boy.
• Mukuro's constant grin. As well as his Evil Eye and his "ku fu fu..." Also, the Path of Humans.
• The shot of Mukuro smiling even after stabbing his own eye out.
• How about the way Mukuro defeated Mammon? He did so by turning into a suspiciously tentacle-like black mass, forcing himself into her his mouth, and making her him explode. All while she he screams for mercy. It might've been Fetish Fuel if Mammon wasn't practically an infant.
• Lussuria's implied necrophiliac tendencies. In his own words, his favorite bodies are the "cold, slowly decomposing, unmoving ones" (he then licks his lips).
• Resident Ill Girl Chrome's abusive parents. She also suffers from Blood From the Mouth whenever her illusionary organs give out. Immensely freakier in the manga where they actually show her coughing up quite a bit of blood.

TYL arc

• The Vongola Boss Right of Passage.
• Bel and Jill, The Bloody Twins
• The Deathstalk Squad.
• Genkishi's death.
• Squalo's getting his arm ripped off.
• Daisy and his... teddy.
• THIS.
  • And in the following chapter it becomes even more disturbing looking.
• This and this. I know they're illusions but dear God they had me terrified...
• What happened to Bluebell. Squick.
• Byakuran getting owned after Giotto broke the Vongola rings into their true forms.
• Byakuran trying to strangle Tsuna while smiling. And then doing the Neck Snap on him.
  • This is toned down in the anime. Instead of the neck, Byakuran was either trying to snap his spine or crush all the bones in his body. Sounds less scary, until you count how many bones AND organs he probably broke this time.
• Tsuna vaporizing Byakuran with his X-burner because he was angry as a result of Gamma and Uni's Heroic Sacrifice. There's also the expression on his face as he tells Byakuran that he won't forgive him and Bykauran loosing his cool following Gamma and Uni's Heroic Sacrifice.

Vongola X Inheritance Ceremony arc

• In chapter 329 Daemon Spade orders Enma to "take Sawada's skull and crush it like glass", and then he laughs maniacally...
• When Kaoru made Yamamoto a bloody mess.
• THIS is Enma after he crossed the Despair Event Horizon. Dear god, Body Horror doesn't even BEGIN to describe how frightening this is. Poor Enma...
  • Upon seeing that, I actually thought that Xanxus just might be getting one-upped in the "psychotic rage" department.
  • His appearance is probably the most disturbing thing about this usual tame series.
• Daemon Spade, just Daemon Spade. If you thought Mukuro was bad, he is even worse in how he obtains his goals, and normally he shouldn't even be alive in the current storyline due to being one of Primo's Guardians.
• Daemon Spade here from chapter 335.
• Chapter 337 gets even worse.
  • By the end of the final battle, he ends up looking like something that would make Father horny.

Curse Of the Arcobaleno arc

• This from chapter 366. The External Open Carnage Box.
• Mukuro's new illusion from chapter 381. Corpse eating crows. Which he proceeds to use on the Vindice. He was gonna use it on Tsuna to defeat him.
  • We also get to see what Vindice looks like without their hats and cloaks. It is not pretty.