"Wristcut": Mr. Shinohara, the chemistry teacher of Itsuki Kamiyama and Yoru Morino, is a lunatic with a fetish for slashing off the hands of innocent people, even lopping off the paws of animals and cutting off the hands of children. Shinohara finally graduates to full-on murder when he kidnaps and kills a local celebrity for her hands, and when he's convinced to believe Morino stole his collection of hands, Shinohara attempts to murder her in berserk rage.
"Goth": The seemingly-innocuous cafe manager is secretly a Serial Killer who sadistically mutilates and murders women, before cataloging the gory details of his kill in his notebook. A hateful misogynist, the manager tells his victims they are guilty sinners who deserve to die. Capturing Morino, the manager only keeps her alive for the time being out of fear the police are on his tracks while telling the captive girl how much he looks forward to brutally killing her.
Nightmare Fuel: The things most of the criminals encountered do in the stories. Chopping off hands (including those of a baby), murdering people and spreading their organs around, leaving people to die buried underground... wherever the main characters live must be a pretty grim place.
The 2008 live-action film
Complete Monster: The film amalgamates the characteristics of the manga's first and second chapters' killers. Obsessed with beauty, this version of the cafe manager kidnaps women, chopping off and keeping their hands, then leaves the corpses in public places to create his depraved aesthetic. Linked to deaths of four women, the manager nearly kills Yu/Yoru Morino as well. Stopped by Itsuki Kamiyama revealing he holds the manager's journal detailing his entire modus operandi and forced to flee town, he no doubt intends to pursue more victims.
