Full frontal female nudity (no nipple detail) in the Imaginator vs Boogiepop arc.

Horror violence is in the series. Though most of the violence isn't that bad some of it is pretty brutal and somewhat graphic.

Both fictional and real drugs are present throughout the series. Some character are addicted to drugs.

One villain slips a drug in a high school girl's drink.

Quite scary, all of the villains are scary and or creepy. Psychological horror present throughout the whole series.

One villain feeds off fear, she actively tries to scare other characters in order to get nourishment from their fear. Some of the ways she scares other characters is quite disturbing.

Most of the horror is psychological so it might go over some people's heads. But with that said the horror is terrifying once you think about it.