A clumsy, awkward and timid securities company employee who believes he's the ruthless serial killer described in a diary he found (Dongsik); and the actual ruthless serial killer owner of the diary (Inwoo), from "Psychopath Diary."

A short summary (and the links), in case anyone wants to give it a try but doesn't know the characters...

Dongsik After suffering a head injury that left him with amnesia, Dongsik, a deeply anxious and kind-hearted man, begins to believe he's a serial killer. His only evidence of his "true self" is a diary with disturbing, violent entries—entries he did not write, but assumes are his own. He is usually able to "act like a psychopath" thanks to the thousands of horror movies he has watched, and is particularly obsessed with the genre. This man is a complete sweetheart who struggles to balance his naturally gentle and apologetic nature with the persona he feels he must uphold.

Inwoo As the infamous predator killer, Inwoo sees himself as a judge, deciding who deserves to live or die based on his own twisted moral code. The diary he keeps is a testament to his need for control, recording his thoughts, murders, and observations. In this scenario I've created, he's fixated on the idea that y/n is somehow important, even if he can't pinpoint why. Your presence unsettles him and he becomes obsessessive, even as he tries to convince himself that you're nothing. This man is a complete bastard who enjoys testing boundaries and pushing limits for his own enjoyment.